PSU for a gaming machine

[haris25]

Hi everyone, Needed your help with the selection of a PSU. The ones available in market are Cooler Master GX series and the Corsair VS series.

I will be needing a 650 WATT power supply. Although the card, that I have selected is a GTX 660Ti which requires a 450Watt PSU but as part of planning for the future I will be going for a 650 WATT PSU. 650 watt products in my market include the
Corsair VS 650
Cooler MAster GX 650.

I wont be using a SLI or Crossfire setup or overclocking. As such I wont buy a 750W or higher PSU.

Needed you help.

 

[Cons29]

avoid the cooler master, they have bad rep, not sure if they are ok now but there are lots of other choices so take those instead

 

[haris25]

Thank you for the reply. The issue is that the only PSUs in the 600-650Watt category available in my market are either Cooler MAster or Corsair. And the only corsair product in my market in this category is the VS 650. What would you sugget?

 

[flong777]

Thank you for the reply. The issue is that the only PSUs in the 600-650Watt category available in my market are either Cooler MAster or Corsair. And the only corsair product in my market in this category is the VS 650. What would you sugget?

I don't think that Corsair makes a "VS 650." They make a TX 650 and a GS 600 and a CX 600 and a HX 650. Any of these would be the better choice. Corsair really backs their products and the PSUs are some of the best available. I have not read a bad review on a Corsair PSU. The TX 650 and the HX 650 would be the best choices if your budget allows (they are more expensive).

If you are going to use multiple GPUs in crossfire or SLI look at the Corsair HX 850.

 

[Cons29]

corsair sells great psu's (some of their products are made by Seasonic, my favorite)

 

[4745454b]

If you aren't going CF/SLI, you don't need a 650W PSU. A GOOD 450-500W will do fine.

Any 80bronze rated units where you are?

 

[flong777]

If you aren't going CF/SLI, you don't need a 650W PSU. A GOOD 450-500W will do fine.

Any 80bronze rated units where you are?

Most GPU / CPU combos draw 250W - 300W depending on many factors and add another GPU and you are way past the capacity of a 450W PSU. A 650W PSU would be a minimum for crossfire or SLI and I would not recommend that small a PSU.

The Corsair CX 600 is dirt cheap (something like $70) and it would provide plenty of power for a single GPU. The TX 650 is also a good choice and is a step up from the CX 600.

I am not a fan of 450W - 500W PSUs simply because they are not much cheaper than something like the Corsair CX 600. Plus they tend to have quality control problems and they leave you no room to upgrade. I have had problems with low wattage PSUs.

You probably could run a 2-GPU build off of the Corsair TX 650 although I would not recommend it.

 

[4745454b]

Did you read the OP?

I wont be using a SLI or Crossfire setup or overclocking.

He already said only one GPU. 300W for a beefy GPU and CPU, maybe a bit more for the rest of the system. When I researched my 7950 the system draw is around 325W depending on which card. We don't know anything about his system, but I'm guessing from the lower end PSUs he's looking at it's not a huge system. A 500W Corsair will power a 7950 just fine.

 

[flong777]

Did you read the OP?

I wont be using a SLI or Crossfire setup or overclocking.

He already said only one GPU. 300W for a beefy GPU and CPU, maybe a bit more for the rest of the system. When I researched my 7950 the system draw is around 325W depending on which card. We don't know anything about his system, but I'm guessing from the lower end PSUs he's looking at it's not a huge system. A 500W Corsair will power a 7950 just fine.

Agreed - I say that in my previous post. However I don't like the 450-500W PSUs for a number of reasons. The biggest reason is efficiency. If you are running a single GPU build you probably are drawing at least 400W, maybe more. This means that you are maxing out the PSU capacity and this is never a good scenario.

Also, many of the 450-500W PSUs don't actually supply that much wattage. You are right that Corsair probably does but still you have very little head room.

All PSUs run most efficiently when running at 50% of their capacity. This means if you kick your PSU up to the 600 - 650W range, your PSU will run much more efficiently, quietly and will be more cool in the case.

Add to this the fact that the Corsair CX 600 is something like $70 after rebates and I just don't see the wisdom of downgrading for a $20 saving.

I agree with you and you are correct that a 450-500W PSU will run a single GPU computer. I just don't think it is the best choice.

 

[4745454b]

You say 50% like thats the only range. I think its around 50-80%? I know by 100% you are "allowed" to go back to your 20% load figures. 75% or so isn't going to be, or rather shouldn't be any worse then 50%. 400W? 7950W using around 325? Even using your 400W figure that's still only 80% of the 500W PSU. As long as we are talking about a QUALITY PSU 80% is nothing. Check out the torture test that HardOCP uses in their reviews. 80% load for 8hrs. Nearly always has same figures from their Test 3 which is ~75%.

http://www.hardocp.com/article/2013/03/14/silverstone_sfx_st45sfg_450w_power_supply_review/6

 

[4745454b]

LOL, as an aside I don't like the 650W units. To much for one GPU, and not usually enough for two. (The new 80gold units are an exception.) 500W for one GPU, 750+ for duals.

 

[flong777]

You say 50% like thats the only range. I think its around 50-80%? I know by 100% you are "allowed" to go back to your 20% load figures. 75% or so isn't going to be, or rather shouldn't be any worse then 50%. 400W? 7950W using around 325? Even using your 400W figure that's still only 80% of the 500W PSU. As long as we are talking about a QUALITY PSU 80% is nothing. Check out the torture test that HardOCP uses in their reviews. 80% load for 8hrs. Nearly always has same figures from their Test 3 which is ~75%.

http://www.hardocp.com/article/2013/03/14/silverstone_sfx_st45sfg_450w_power_supply_review/6

I am not sure that you are reading AND understanding my post. Look up above again and you will see that I said that I agree with you that a 500W PSU will run a single GPU build.

The OCP torture test on the Silverstone PSU that you posted verify what I am saying. It runs at 90% efficiency at 222W. From there your efficiency goes down hill and your PSU heats up. This would not occur with a 650W PSU because you would be near 50% capacity.

You see the question is not what will work, the question is, "what will work the best." I size all my builds with a 50% over-capacity in the CPU. This ensures that my PSU will be running at maximum efficiency. The cost difference is very little to achieve this.

My computer has a lot of components and so I actually went to the Corsair HX 850 because my computer will be using approximately 400W of power (2600K with a ATI 6950 GPU and other components). Yes it is overkill but my PSU only cost $144.00 and it comes with a 7-year warranty. I can easily run a second GPU AND overclock with this GPU and I don't have to buy a bigger one to do it.

Also, as I said before, because the smaller PSUs are used by mass builders like Dell, they often run into quality control problems. Dell gambles that the 450W PSUs they put in their computers won't burn out their components before the warranty is up.

Reasonable people can disagree. My Corsair HX 850 runs silent and cool in my case and according to the reviews I have read, it is running at 92%-93% efficiency. It is one of the most stable PSUs on the market. To me that is worth an extra $50-$75. Not everyone feels the same way.

 

[flong777]

LOL, as an aside I don't like the 650W units. To much for one GPU, and not usually enough for two. (The new 80gold units are an exception.) 500W for one GPU, 750+ for duals.

If you are backing a 500W for one GPU, then you logically think that a 650W PSU will run two GPUs. Your GPU / CPU draw would be 500 -550W approximately (depending on a number of factors). If you are not running a lot of fans the 650W will carry a two GPU build but not with much headroom. It will be close to the headroom for the 500W PSU build you are recommending.

 

[4745454b]

You've got load locked up, but what about idle? A machine at idlelow load should be around 100W. For a 500W, this is 20%. For 650W, this is 15%. I'd rather have the slightly lower load efficiency for the better idle. Not to mention "my" 500W unit is probably a bit cheaper then "your" 650W. (Though sales can/will change this.)

 

[flong777]

You've got load locked up, but what about idle? A machine at idlelow load should be around 100W. For a 500W, this is 20%. For 650W, this is 15%. I'd rather have the slightly lower load efficiency for the better idle. Not to mention "my" 500W unit is probably a bit cheaper then "your" 650W. (Though sales can/will change this.)

That is a good point and I did think of this. With my own PSU, the Corsair HX 850, as the load drops to 30% the efficiency only drops to around 91% efficiency and so I am covered. Remember that just your CPU, GPU, fans and CPU cooler will easily bring you to the 300W level and can quickly go higher. Most computers don't spend much time at idle - at least mine doesn't.

But if you do size your PSU at 50% over-capacity as I did, you have to make sure that your PSU has a wide enough efficiency range so that if you do drop down to 30% capacity (which would probably be your minimum) your efficiency doesn't go through the floor. With most quality PSUs this won't be a problem. Most PSUs are in their most efficient range from 30% - 50% capacity.

The problems with running without much headroom are far more severe than the problems caused by running a 30% capacity. I am much more concerned about lack of stability, over-heating and high-fan noise than I am about losing 1%-3% of efficiency.

Again, not everyone feels the same way and I understand that.

 

[4745454b]

Fans aren't going to bring you up to 300W. And by idle I didn't mean true idle, but also surfing and movie watching. With such a little load on the system, you'll be at 100W give or take while doing this. 850W? Lets see, carry the 1, what do we do with remainders again? ~12%? Though if you hit 91% then you probably have a gold PSU.

You don't need to buy a PSU that gives you no headroom. But there isn't much point in buying a 650W PSU for a 77W CPU and whatever GPU he picked. Even if he went with a 125W AMD chip and a 7970, he is still looking at around 425W load. 550W is still only 77%. 650W isn't bad, but not needed. And assuming the 650W costs more, might be the wrong choice.

 

[flong777]

Fans aren't going to bring you up to 300W. And by idle I didn't mean true idle, but also surfing and movie watching. With such a little load on the system, you'll be at 100W give or take while doing this. 850W? Lets see, carry the 1, what do we do with remainders again? ~12%? Though if you hit 91% then you probably have a gold PSU.

You don't need to buy a PSU that gives you no headroom. But there isn't much point in buying a 650W PSU for a 77W CPU and whatever GPU he picked. Even if he went with a 125W AMD chip and a 7970, he is still looking at around 425W load. 550W is still only 77%. 650W isn't bad, but not needed. And assuming the 650W costs more, might be the wrong choice.

I am not sure that your "idle" at 100W is accurate. Granted I could be wrong but your GPU is always working a fair amount depending on your resolution and screen size and the CPU can run wattage up very quickly also. I have never measured the draw first hand but I have read reviews by people who did.

If your idle number is correct than the 500W PSU would be VERY inefficient because they suck big time at low wattage draws in the reviews I have read. The better your PSU, the better it will handle low power draw situations.

For example, the AX 1200 (and probably the 1200i also) will run at nearly 88% efficiency with a draw of just over 220W. This is really amazing considering the size of the PSU. So the size of the PSU does not necessarily tell you how well it will handle the "idle" situations that you are describing. It is the quality of the PSU that determines how efficient it is a low draw situations.

For example this Xbit review of the AX 1200i shows that it hits 90% efficiency at approximately 150W which is spectacular for a 1200W unit.
The link is here: http://www.xbitlabs.com/articles/cases/display/corsair-ax-axi.html

Conversely the cheaper 450-500W units do not function well at all in low draw situations and are severely affected. This is why I am hesitant to even recommend the CX 600. But my trust in Corsair quality pushes me over the edge to recommend this $70 PSU.

I get what you are saying and you were right from the start, a 500W PSU will work. But it won't work as well as a AX 1200i in any situation, or an HX 850 or a TX 650 or a CX 600.

A quality PSU is very important and people often cut corners with the PSU. I agree up to a point but that point ends at the $70 CX 600 (which can be bought on sale even cheaper). Different people can reasonably disagree.

BTW, after reading the amazing efficiency number of the AX 1200, I would have bought it but I found a screaming deal on the HX 850 ($144) that I couldn't turn down. Now that would have REALLY been overkill but it would have given me 90% efficiency, a 7-year warranty and more than enough power to do ANYTHING I want in the future. And PSU technology isn't going to change that much in the future. I just say this for your amusement because the 1200W PSU on a single GPU build really amuses me lol. But there is no denying the numbers, especially for the 1200i.

 

[4745454b]

Gold and higher units are a different breed. In order to hit 88%+ efficiency at 20%+ they tend to be efficient no matter where they are. I haven't checked, but look at an 80Bronze 1kW unit. Check out there 10% load if you can even find that data. 88%? Probably more like 75%

I'm about to dump my current PSU. I bought it when I hadn't nailed down what GPU(s) I'd be using. I bought an Antec 750Green. I wanted a decent PSU that could handle any two GPUs I threw at it. Problem is I settled on a single 7950. Now I get to dump my current PSU and get something more suited to what I need. And seeing as I have the money, I'm looking at a good 450-500W gold/platinum unit. As stated above, this should be way efficient no matter what I'm doing. Unlike my current 750W.

I could be wrong but your GPU is always working a fair amount depending on your resolution and screen size

If you are just sitting on the desktop or watching youtube, its very low. 2D clocks and built in functions to the GPU die are great for lowering power usage.

While that 52W is for the card only, your CPU shouldn't be running very hard at all. Assuming a 77W Intel quad, I'd bet it would be at half if not lower. Even if I'm wrong, 52+ 40 + 40 for rest of system is ~130W. Trust me, running a modern system while just surfing or watching a movie doesn't use a lot of power. And I don't know about you, but most of what I do is surf or watch. I game a bit on my weekends so I need a PSU good/large enough to handle that. But not at the expense of what I do 80%+ of the time.

Edit: Link to graph.

http://www.techpowerup.com/reviews/AMD/HD_7950/25.html

Another way to look at it is to add the ~40W needed to go from idle to Blu ray to another site that lists the system idle. This 40W should be the increase in the card. Toms had their 7950 system idling around 103W, so 143W wouldn't be out of line. Sounds high to me but it is what it is.

 

[flong777]

Gold and higher units are a different breed. In order to hit 88%+ efficiency at 20%+ they tend to be efficient no matter where they are. I haven't checked, but look at an 80Bronze 1kW unit. Check out there 10% load if you can even find that data. 88%? Probably more like 75%

I'm about to dump my current PSU. I bought it when I hadn't nailed down what GPU(s) I'd be using. I bought an Antec 750Green. I wanted a decent PSU that could handle any two GPUs I threw at it. Problem is I settled on a single 7950. Now I get to dump my current PSU and get something more suited to what I need. And seeing as I have the money, I'm looking at a good 450-500W gold/platinum unit. As stated above, this should be way efficient no matter what I'm doing. Unlike my current 750W.

I could be wrong but your GPU is always working a fair amount depending on your resolution and screen size

If you are just sitting on the desktop or watching youtube, its very low. 2D clocks and built in functions to the GPU die are great for lowering power usage.

While that 52W is for the card only, your CPU shouldn't be running very hard at all. Assuming a 77W Intel quad, I'd bet it would be at half if not lower. Even if I'm wrong, 52+ 40 + 40 for rest of system is ~130W. Trust me, running a modern system while just surfing or watching a movie doesn't use a lot of power. And I don't know about you, but most of what I do is surf or watch. I game a bit on my weekends so I need a PSU good/large enough to handle that. But not at the expense of what I do 80%+ of the time.

Edit: Link to graph.

http://www.techpowerup.com/reviews/AMD/HD_7950/25.html

Another way to look at it is to add the ~40W needed to go from idle to Blu ray to another site that lists the system idle. This 40W should be the increase in the card. Toms had their 7950 system idling around 103W, so 143W wouldn't be out of line. Sounds high to me but it is what it is.

Great post, you took the time to look up the actual figures. Going by those figures the PC would probably be in the 200W-250W range.

I have an inherrant distrust of the 450W -550W PSUs because so many builders like Dell use them and they are mass produced very cheaply . This causes a lot of quality control issues.

For example, Corsair's CX600 is an excellent buy bronze rated PSU but if you check the Newegg reviews a LOT of units arrive DOA and Corsair is one of the best out there.

If you are talking about going to a gold or platinum 450W - 550W PSU, then yes you probably avoid the QC problems of the bronze units but again you leave no room for any real changes in your computer. Even more importantly, these units cost just about as much as a gold 650W unit or even my HX 850 if you catch a sale. So I don't see the value of a gold rated 450W unit and there aren't many of them to choose from.

I agree with you and I appreciate your taking the time to look up actual power draws. In the reviews that I have read the 650W PSUs have a much better quality control level and that is why I think they are the best choice. They often don't cost a whole lot more and overall their quality is superior (in professional reviews). For 450-600W PSUs it is sometimes hard to find a single professional review - try finding one for the Corsair CX 600, I couldn't find a single review with a Google search.

I try to read every PSU professional review that comes out as this subject interests me. I particularly like Johnny Guru's reviews (they are funny).

You are absolutely correct and I have said that from the beginning, a 500W PSU will run a single GPU build, no doubt. My choice of the 650W as a base unit is based on a big-picture review of quality vs cost vs efficiency. There is a LOT of room for reasonable people to disagree.

Also while I agree with the numbers you list for draw on the PSU, I am not sure that even those professional review numbers are always accurate. For example, I had a Corsair HX 750 with an I-7 920 single GPU build and incredibly, the HX 750 would ramp up to high fan all the time. Part of it was caused by the case not cooling well but part of it was actual power draw because this would happen when I had a lot of applications open. Professional reviews said that this PSU would put out 900W and remain stable and so I was profoundly disappointed.

I distrust power draw numbers that we see in reviews because they are usually taken during ideal situations and they don't take into account inefficiencies, heat and other factors. This is one of the main reasons I like a lot of headroom on my PSUs.

So the quality control of bronze 450-550W PSUs and my distrust of review numbers and the lack of reviews of lower wattage PSUs all provide a profound distrust in me of them and I am loathe to recommend them. Yes a lot of people (even Dell) use them and don't have problems but I don't like the risk factor.

I know that my system which draws between 300W - 400W runs exceptional well with the HX 850 and it was actually CHEAPER than the HX 750 or many 650W PSUs at the time I purchased it ($144 after rebate). I have never even heard the PSU fan turn on (I'm sure it must go to low fan some time) - the PSU runs completely silent and cool. This tells me it is in its max efficiency range. The HX 850 is a gold rated PSU.

For builders who can afford it, I would recommend the AX 1200i in a heartbeat and I would buy it myself if I needed a PSU. You simply would have a PSU that would last a lifetime (7-year warranty) that is over 90% efficient all of the time on any build you could dream of. But yes it is huge overkill I ABSOLUTELY agree with you.

For people with a reasonable budget, a quality 650W PSU up to my HX 850 depending on what is on sale are all good choices that give me peace of mind. The 450W - 550W PSUs don't give me peace of mind and that is why I don't recommend them. I don't recommend what I personally would not use and don't trust.

You make a very good argument for the low wattage PSUs but I simply don't trust them. Thanks again for your high quality posts.

 

[4745454b]

Great post, you took the time to look up the actual figures. Going by those figures the PC would probably be in the 200W-250W range.

How do you figure? Idle is around 100W, how do you get 250W watching a movie?

I have an inherrant distrust of the 450W -550W PSUs because so many builders like Dell use them and they are mass produced very cheaply . This causes a lot of quality control issues.

Yes, if you are lucky. (most are even smaller then 450W.) But those are "bestec" or other such PSUs. Not Antec or Corsair PSUs that are made by Seasonic, Delta, or CWT. Big difference between OEM 450W and name brand 450W.

The mod in me is starting to wonder if we are losing the OP and if he is even around anymore. It's been very nice talking to you about this as you've actually replied with some reasonable things and not just saying I'm a poppy head. A breath of fresh air I assure you. Buying a 650W might get you a few more % points at load, but I'm very confident that you will be hurting at idle/low load. It might depend on where you spend the most amount of time. (might also depend on what you need to run. If you are going CF 7970s or something like that, you have no choice but to run a 750W+ unit. Idle be damned.) As I often do I'm going to take the high road at this point and let the OP read and try to make up his own mind. 500W will be fine. It won't die as long as its a good one. 650W will also be fine. But assuming the 650W is more expensive, you don't HAVE to buy it. As mentioned a smaller unit will do.

 

[flong777]

Great post, you took the time to look up the actual figures. Going by those figures the PC would probably be in the 200W-250W range.

How do you figure? Idle is around 100W, how do you get 250W watching a movie?

I have an inherrant distrust of the 450W -550W PSUs because so many builders like Dell use them and they are mass produced very cheaply . This causes a lot of quality control issues.

Yes, if you are lucky. (most are even smaller then 450W.) But those are "bestec" or other such PSUs. Not Antec or Corsair PSUs that are made by Seasonic, Delta, or CWT. Big difference between OEM 450W and name brand 450W.

The mod in me is starting to wonder if we are losing the OP and if he is even around anymore. It's been very nice talking to you about this as you've actually replied with some reasonable things and not just saying I'm a poppy head. A breath of fresh air I assure you. Buying a 650W might get you a few more % points at load, but I'm very confident that you will be hurting at idle/low load. It might depend on where you spend the most amount of time. (might also depend on what you need to run. If you are going CF 7970s or something like that, you have no choice but to run a 750W+ unit. Idle be damned.) As I often do I'm going to take the high road at this point and let the OP read and try to make up his own mind. 500W will be fine. It won't die as long as its a good one. 650W will also be fine. But assuming the 650W is more expensive, you don't HAVE to buy it. As mentioned a smaller unit will do.

Agreed poppy head lol (I'm joking of course)

 

[flong777]

Great post, you took the time to look up the actual figures. Going by those figures the PC would probably be in the 200W-250W range.

How do you figure? Idle is around 100W, how do you get 250W watching a movie?

I have an inherrant distrust of the 450W -550W PSUs because so many builders like Dell use them and they are mass produced very cheaply . This causes a lot of quality control issues.

Yes, if you are lucky. (most are even smaller then 450W.) But those are "bestec" or other such PSUs. Not Antec or Corsair PSUs that are made by Seasonic, Delta, or CWT. Big difference between OEM 450W and name brand 450W.

The mod in me is starting to wonder if we are losing the OP and if he is even around anymore. It's been very nice talking to you about this as you've actually replied with some reasonable things and not just saying I'm a poppy head. A breath of fresh air I assure you. Buying a 650W might get you a few more % points at load, but I'm very confident that you will be hurting at idle/low load. It might depend on where you spend the most amount of time. (might also depend on what you need to run. If you are going CF 7970s or something like that, you have no choice but to run a 750W+ unit. Idle be damned.) As I often do I'm going to take the high road at this point and let the OP read and try to make up his own mind. 500W will be fine. It won't die as long as its a good one. 650W will also be fine. But assuming the 650W is more expensive, you don't HAVE to buy it. As mentioned a smaller unit will do.

You quick question, I have never seen idle loads as low as 100W listed in professional reviews can you tell me how you are computing that number. I an sincerely interested in this.

Also in most good professional reviews they do a "low load" test which is usually around 40W-60W (or less). My PSU (HX850) was around 85% efficient, the AX 1200i is around 87% efficient at these low load tests. A quality PSU will perform at 100W. At 150W the AX1200i is 90% efficient. So depending on the quality of the PSU, you are covered for low loads. It is the cheaper bronze (and some silver) units that lose all efficiency at low wattages.

 

[4745454b]

Professional reviews for PSUs or GPUs? PSUs I'm sure you've seen, I know JG does them.

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=318

Here is your stand by and low load test. I tried to find a review of a non gold+ unit, but all of those didn't have the standby tests.

As for the GPU, here is what Toms found as their idle load.

That's with the stock 7950 and an i7-3960X OC'd to 4.2GHz. Having a system idle of 102W is really impressive in this case. Obviously if you have a stock clocked CPU or one less powerful then sub 100W is very possible. What I had issues finding was load info while doing something basic like watching a movie or surfing youtube. The previous graph was as close as I could find. Most of AMDs current chips can hit the sub 20W idle so they should all be around this. This is why I'm not a fan of the 650W units. Because if its going to cost me more to buy it over a 500W, and if the efficiency isn't as good at this low of a load, then I'm just spending money I shouldn't. But we already went over that.

 

[flong777]

Professional reviews for PSUs or GPUs? PSUs I'm sure you've seen, I know JG does them.

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=318

Here is your stand by and low load test. I tried to find a review of a non gold+ unit, but all of those didn't have the standby tests.

As for the GPU, here is what Toms found as their idle load.

That's with the stock 7950 and an i7-3960X OC'd to 4.2GHz. Having a system idle of 102W is really impressive in this case. Obviously if you have a stock clocked CPU or one less powerful then sub 100W is very possible. What I had issues finding was load info while doing something basic like watching a movie or surfing youtube. The previous graph was as close as I could find. Most of AMDs current chips can hit the sub 20W idle so they should all be around this. This is why I'm not a fan of the 650W units. Because if its going to cost me more to buy it over a 500W, and if the efficiency isn't as good at this low of a load, then I'm just spending money I shouldn't. But we already went over that.

So the above TH "Idle Chart" is a measure of the computer with no applications running?

Also, wattage aside most of the bronze and some silver PSUs efficiency drops very badly for PSUs of any wattage. So getting a smaller PSU in the 400W - 600W range does not protect you against loss of efficiency at low loads. The problem is that the lower quality PSUs cannot adjust to low power usage. I have read this problem occurring with some Antec units and I think one or two Seasonic PSUs which were bronze rated - but that is off the top of my head.

If you go to a gold rated 450W -550W PSU (and there are not many to choose from and they are expensive) you do get better low power performance but you get the same low power efficiency performance from 650W -1200W gold and platinum PSUs from Seasonic and Corsair (I am not a big Antec fan). You see what I mean? It is the quality of the PSU not the wattage that determines it's low power efficiency.

Here is the latest review for the HX 850 at Johnny Guru:
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story2&reid=299

Keep in mind that his efficiency numbers are usually 2%-3% lower than most other professional reviewer's numbers for some reason. The chart shows that my unit is running at 83.4% efficiency at 102W - this is for the "Low Load Test." Most other websites put this efficiency at 85% - 86% (I read every review on the planet before I bought the HX 850).

Even with very limited use my computer will probably be drawing 175W which puts me in the 89.1% range (for Johnny Guru figures, which again are lower than most other professional reviewers for some reason). So you see I am nearly always running in the 90% - 92% efficiency range with a single GPU, 2600K, two optical drives, 2 HDDs, 2 SSDs, Nocuta NH-D14 cooler, 6 case fans, Hauppauge 2250 HDTV Card, Asus sound card.

This results will be repeated with a high quality 650W PSU at 100W. Bronze efficiency for a 450W - 550W will probably drop in to 72% range at 100W (some go into the 60% range).

I posted this Johnny Guru review to show you how a HX 850 will run very efficiently from the 100W - 200W range on a single GPU build. You are getting 84% -90% efficiency numbers - higher if you don't use Johnny Guru efficiency numbers.

 

[Kisianik]

Thank you for the reply. The issue is that the only PSUs in the 600-650Watt category available in my market are either Cooler MAster or Corsair. And the only corsair product in my market in this category is the VS 650. What would you sugget?

The situation here is a little bit different, since OP lives overseas somewhere, I seen people asking about Corsair VS and they were located in Middle East, I was looking for regular Corsair series there, but could not find any.

So, stop suggesting what OP can not buy.
Please come up with recommended wattage and I will look for suppliers locally.
haris25 were do you live, which country? Last time I seen similar situation, it was Pakistan.