Picking The Right Power Supply: What You Should Know (Archive)

[dgingeri]

I had a cheap power supply take out my nephew's computer a while back. The fan quit and solder melted and cross connected the 12V rail to the 5V rail, and 12V or 17V went through everything hooked to the 5V rail. The motherboard would power up, but it wouldn't see any PCI devices, including the southbridge. All the drives were dead, but the processor and memory were fine. It was a bad situation. I ended up building a whole new PC for him because there wasn't anything I could salvage and use. (The processor and memory were just too outdated, being a Duron 600 and SDR memory.)

Cheap power supplies are not worth the trouble. To this day, I never buy a case with a power supply, or if I do, I don't use the one that came with it. I buy all my power supplies from known good vendors: Silverstone, Thermaltake, Antec, and Enermax.

 

[ram1009]

[citation][nom]SteelCity1981[/nom]Like the old saying goes... "You get what you pay for."[/citation]
So, let's see. If I made a POS PSU and charged a lot of money for it you'd buy it?

 

[sebastianem]

This article was outstanding! Good info for those who don't know what they are getting into or fall victim to marketing hype (DragonMegaHyperCombatUltra PSU - that was pure awesome, BTW!).
Not to take away from Tom's, but another good place to investigate PSU's is [H]ard OCP:

www.hardocp.com

They don't play around when it comes to PSU reviews and they explain in great detail how and why they do what they do.

 

[phaedrus2129]

So, let's see. If I made a POS PSU and charged a lot of money for it you'd buy it?

I prefer the variant, "You don't get what you don't pay for."

 

[ram1009]

I disagree totally with the #2 conclusion. No PSU should ever be run at more than 50% of its actual capacity. If we were talking about big money here I might feel differently but for a relative pittance you can get a higher wattage PSU which you will never overstress. It's cheap insurance any way you look at it.

 

[phaedrus2129]

I disagree totally with the #2 conclusion. No PSU should ever be run at more than 50% of its actual capacity. If we were talking about big money here I might feel differently but for a relative pittance you can get a higher wattage PSU which you will never overstress. It's cheap insurance any way you look at it.

Refusing to run a quality PSU at over 50% of its rated wattage is an insult to the engineers who designed it. Especially since most quality units can still safely provide 30-50% more than what they're rated for, but are rated lower to meet efficiency standards and prolong lifespan.

 

[Guest]

"You can’t get a good 500 W power supply for 40 bucks."
Really? FSP Saga II 500 W for $40 is a great power supply and people I know have run a Phenom ii x4 955 and an HD 6850 on it.

 

[mariush]

One thing that is not mentioned in the article is that as cheaper power supplies are delivering power close to their maximum capabilities, the quality of the output often degrades.

When stressed, these cheaper power supplies will cause "ripple" on the output cables, the voltage will fluctuate a lot and circuitry inside the computer (on the motherboard, on the video card) has to work harder than they were designed to filter and give smooth power to the CPU or the video card.

So it may work now but you may also find out after a year that the motherboard or the video card dies or just that you can't overclock the CPU as you used to.

 

[Onus]

I thought this was article made its points fairly well. Even though it was not as technical as some of the material at HardwareSecrets, it was in some cases more practical. When sizing a PSU, I know I am far less extravagant than many, but it reminded me... A quality PSU is typically UNDER-rated. Gabriel Torres is the only reviewer I know who consistently attempts to test how much power a given PSU can actually provide in excess of its label (where it hasn't already failed), and in almost every case, he is able to exceed the label by a considerable margin (e.g. my SG-650 can output 840W, a huge increase). So, that "margin of safety" we (myself included) often suggest is actually already built in to a better PSU. I will keep that in mind for future recommendations.

 

[ram1009]

Refusing to run a quality PSU at over 50% of its rated wattage is an insult to the engineers who designed it. Especially since most quality units can still safely provide 30-50% more than what they're rated for, but are rated lower to meet efficiency standards and prolong lifespan.

At the risk of insulting "the PSU guru" as well, any designer who is insulted by having his end user take extra precautions with his designs has a rather large ego to say the least. I'd like nothing better than for my designs to be treated with this degree of respect. In reality, the designer would never know or care. My position is a simple matter of common sense.

 

[Pekish79]

I wonder how u generated the Load power draw in the enthusiastic pc i have very similar spec and cant get more then 400W

i5 2500K OC@4.5 + Noctua Nh-U9B
GTX gigabyte 580 OC@900-4200
2x4gb g.skill ECO 1,35V
2xSSD intel 80gb X25M-G2 (not in raid)
case Lian-li PC-A04 (with 3fan +1 optional installed Noctua 8cm)
M-atx MSI Z68-ED55
NO DVD
Mouse/Keyboard

I use as psu a Kingwin Lazer Platinum 550W
i just wonder what program/bench u use to get that load

 

[razor512]

how about this, everyone just do it, get a high quality power supply. ATX specs rarely change so get a quality one that has lots of power so it can last you through many future computer builds and upgrades.

It is better to spend $110-150 on a decent 750 watt power supply and have it last years and supply it's full power reliably, instead of spending $50 on one and and replacing it every year or 2 and risk having it take your motherboard, CPU, memory and other components with it.

 

[Scotty99]

I have built around 6 systems with el-cheapo power supplies, and have yet to have a failure within 5 years on any of them. Most were 350watt rosewills, and a couple that i have no idea what they were. I have also built systems with antecs and corsairs, also with zero issues.

Am i just lucky? Perhaps. All i know is that when you are building a PC for someone on a STRICT budget, a power supply (in my experiences) is actually something you can skimp on (given you are not running a high watt CPU or GPU).

I personally use a antec HCG series 520watt because i have a power hungry GPU, prior to this i had a rosewill 350w that came with a case that powered a gt240 for years without issue.

 

[phaedrus2129]

At the risk of insulting "the PSU guru" as well, any designer who is insulted by having his end user take extra precautions with his designs has a rather large ego to say the least. I'd like nothing better than for my designs to be treated with this degree of respect. In reality, the designer would never know or care. My position is a simple matter of common sense.

This part is true. But it is an insult to their competence, assuming that the power supply is so fragile that it can't handle its rated wattage. And by running a PSU below 50% for any reason other than "I had it on hand" or "I'm upgrading in the very near future" is only hurting yourself by spending more money than you have to and running the PSU in a range where it will be very inefficient.

 

[Scotty99]

Also, i laughed a little at the fifth comment on the last page:

Stay away from offers that are too good to be true. You can’t get a good 500 W power supply for 40 bucks. That “bargain” might just blow up in your face. Literally.

I went to newegg and the first thing i saw on the power supply page was this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139027&cm_sp=Cat_Power_Supplies-_-Spotlight-_-17-139-027

Their are 500watt 80 plus (or better) power supplies for 40 bucks all the time. I got my antec 520w 80 plus bronze for 45.00 free shipping.

 

[TeraMedia]

If you're going on newegg, you're probably state-side. European product prices differ significantly. Since the content for this article was developed in Germany, I have to believe that the prices for products available for analysis were probably much higher than what you would typically see.

 

[SteelCity1981]

[citation][nom]ram1009[/nom]So, let's see. If I made a POS PSU and charged a lot of money for it you'd buy it?[/citation]

I guess you don't understand that term, that would be called price guaging not quality based on the materials that go in it.

 

[Guest]

Are the power draw readings listed on this article were measured from the mains? If so, then the actual power consumption of the PC should be somewhat lower (ex. a 350W power draw would translate a 280W for the PC). My 2-year old rig's got similar specs to the listed mid-range machine, except for vidcard which is a Radeon 4770, all running thru a Seasonic S12 II 330W PSU and no problems whatsoever.

 

[karma831]

This article reminded me to swap out the M12D SS-850 in my rig to the SS-560KM that has been sitting in my closet for 2 months.

 

[Stardude82]

Doing a quick search on the "Super Flower" shows it isn't a re-branded Seasonic or something like that. Too bad us in the States are out of luck with that gem.

 

[phaedrus2129]

Doing a quick search on the "Super Flower" shows it isn't a re-branded Seasonic or something like that. Too bad us in the States are out of luck with that gem.

SuperFlower units can be found in the states under the Kingwin brand, and they also sell some 80PLUS Gold units through Rosewill, Xion, and a few other brands.

 

[Pekish79]

yes kingwin = superflower

kingwin LZP-550W Platinum is the one i have that in europe go under the name Super Flower SF-550P14PE

 

[Wish I Was Wealthy]

Nothing new for me,but it's a good read anyway & a good article to read for the beginners.

 

[Proximon]

It's fine as far as it goes, but any such article has to discuss ATX specifications such as voltage regulation and ripple. Neither is that hard to understand.

There are other important things that might not be so easy that could be left out. Transient load spikes for instance.

 

[phaedrus2129]

It's fine as far as it goes, but any such article has to discuss ATX specifications such as voltage regulation and ripple. Neither is that hard to understand.

There are other important things that might not be so easy that could be left out. Transient load spikes for instance.

You could always go by my articles.

http://www.overclock.net/power-supplies/715889-psu-articles.html#post9110838