Undervolting AMD FX-8320?

[FlyingHawk08]

(My first post so may be in wrong section, dunno?)

I'm speculating getting an AMD FX-8320 and undervolting it to reduce its power consumption while keeping to roughly the same clock speed.

Is it a good idea and what voltage should I go down to? (I'm thinking 1.2 or 1.19 - 1.15).

Or should I get an Intel processor in the same price range? (i.e Core i5 3470).


Note: I don't have this cpu now I'm just thinking of what to put in my new build.

 

[8350rocks]

(My first post so may be in wrong section, dunno?)

I'm speculating getting an AMD FX-8320 and undervolting it to reduce its power consumption while keeping to roughly the same clock speed.

Is it a good idea and what voltage should I go down to? (I'm thinking 1.2 or 1.19 - 1.15).

Or should I get an Intel processor in the same price range? (i.e Core i5 3470).


Note: I don't have this cpu now I'm just thinking of what to put in my new build.

The difference in power consumption is about what it costs to run a 40W light bulb over a year...(a few dollars, not significant).

Undervolting a CPU is a bad idea, it makes them run hot...when PC components are power starved they run less efficiently because they're looking for power that isn't there.

The i5-3470 is an option, but the FX8320 you chose is just as good and more cost effective. By the time you add in the higher cost of an intel board it makes less and less sense if your build is budget driven.

 

[FlyingHawk08]

The difference in power consumption is about what it costs to run a 40W light bulb over a year...(a few dollars, not significant).

Undervolting a CPU is a bad idea, it makes them run hot...when PC components are power starved they run less efficiently because they're looking for power that isn't there.

The i5-3470 is an option, but the FX8320 you chose is just as good and more cost effective. By the time you add in the higher cost of an intel board it makes less and less sense if your build is budget driven.

Ah thanks, I might put off undervolting until I understand more and yes I think the FX-8320 has great performance per dollar and also very good bang for buck for my budget build

 

[DarkSable]

The difference in power consumption is about what it costs to run a 40W light bulb over a year...(a few dollars, not significant).

Absolutely correct. Undervolting to try to save money is just silly. As I explain in a minute, undervolting for other reasons makes very good sense.

Undervolting a CPU is a bad idea, it makes them run hot...when PC components are power starved they run less efficiently because they're looking for power that isn't there.

Thank you for giving me my belly laugh of the day. This is so wrong it's not even funny. (Well no, I'm sorry - it's absolutely funny.)

Overvolting a CPU makes it run hotter, because of the increased current. Undervolting a CPU decreses the current and makes it run colder. I don't know where you got your info from, but it's bass-ackwards.

That bit about making them run less efficiently is a particular gem. Running efficiently means using less power. If you force the chip to use less power then... wait for it... it's going to run more efficiently!



EDIT: Just to explain, I de-selected the quoted message as "best-answer" because the OP was acting on faith - something that's completely the opposite of the truth shouldn't be the best answer, because others will find the thread, read it, and believe it, perpetuating this confusion.

Undervolting is nothing but beneficial, and if you can do it, then go for it - but do it to reduce heat, not to reduce your power bill.

 

[8350rocks]

Now, you can underclock your CPU and save power consumption, though that really negates the idea behind buying as much chip as you selected...

Don't worry about the power consumption...the difference is negligible...and with a good, efficient PSU from someone like Corsair or antec or PC Power & Cooling, you'll make up the difference. Just make sure it's at least 80 PLUS Bronze certified or better and you won't notice the difference.

 

[dish_moose]

^^ Thank-you for setting the record straight - I was about to.
-Bruce

 

[8350rocks]

The difference in power consumption is about what it costs to run a 40W light bulb over a year...(a few dollars, not significant).

Absolutely correct. Undervolting to try to save money is just silly. As I explain in a minute, undervolting for other reasons makes very good sense.

Undervolting a CPU is a bad idea, it makes them run hot...when PC components are power starved they run less efficiently because they're looking for power that isn't there.

Thank you for giving me my belly laugh of the day. This is so wrong it's not even funny. (Well no, I'm sorry - it's absolutely funny.)

Overvolting a CPU makes it run hotter, because of the increased current. Undervolting a CPU decreses the current and makes it run colder. I don't know where you got your info from, but it's bass-ackwards.

That bit about making them run less efficiently is a particular gem. Running efficiently means using less power. If you force the chip to use less power then... wait for it... it's going to run more efficiently!



EDIT: Just to explain, I de-selected the quoted message as "best-answer" because the OP was acting on faith - something that's completely the opposite of the truth shouldn't be the best answer, because others will find the thread, read it, and believe it, perpetuating this confusion.

Undervolting is nothing but beneficial, and if you can do it, then go for it - but do it to reduce heat, not to reduce your power bill.

No, you have to reduce clock speed too in order to see this benefit...and the OP was clearly not looking to reduce clock speed. Don't give him bad information...

If you keep the clock multiplier up and reduce the voltage you're going to run hot. It's the same effect that occurs when your PSU goes bad and your components over heat.

Additionally your performance will not be the same when you undervolt the CPU.

Don't mislead someone.

Yes the CPU uses less voltage if you undervolt it, and it will keep temperatures down under reduced load. At increased load temperature increases because the voltage required to run the CPU at higher load isn't there...

Here is an undervolting guide, and even he states the clock multiplier must be reduced to see the gains of these effects:

http://www.silentpcreview.com/article37-page1.html

 

[FlyingHawk08]

I think I can make up for the losses with an 80+ silver psu that I already have (it's a thermaltake toughpower xt 775w I got a while ago, 2 years old)

I might read a bit more on how undervolting and overclocking works
Anyways thanks for the detailed responses.

 

[dish_moose]

If you keep the same clock and are able to reduce the cpu voltage (while stable) the cpu WILL RUN COOLER, and more efficiently.
-Bruce

 

[DarkSable]

No, you have to reduce clock speed too in order to see this benefit...and the OP was clearly not looking to reduce clock speed. Don't give him bad information...

You do not have to reduce clock speed whatsoever. I can run an i5-3570k at stock speeds anywhere from 1.06v to 4.02v (well below stock voltage) before any sort of throttling begins to occur. I'm not giving bad information, I'm giving accurate information.

If you keep the clock multiplier up and reduce the voltage you're going to run hot. It's the same effect that occurs when your PSU goes bad and your components over heat.

This is bad information. Utter BS, and I haven't the slightest idea where you're getting it from - if you stay at stock clocks and undervolt until the CPU begins to throttle, you aren't going to run hot at all, because it's just like overclocking - you're running the chip at the lowest voltage it can use at that clock speed. What you state here is completely wrong.

Additionally your performance will not be the same when you undervolt the CPU.
Don't mislead someone. Yes the CPU uses less voltage if you undervolt it, and it will keep temperatures down under reduced load. At increased load temperature increases because the voltage required to run the CPU at higher load isn't there...

If you could stop accusing me of misleading people, yes, as long as you don't downclock the CPU but only undervolt it, your performance will be exactly the same, because you're running the chip at the same speed.

Also, how in the world would the chip needing more voltage increase heat? What drugs give these ideas - both of you seem to think that, and it's absolutely incorrect. If you aren't giving the chip enough voltage, it won't boot, just like how if you overclock it too far, it won't boot until you give it more voltage.

There is no possible way that undervolting increases heat. If you do it correctly, there is also no possible way that it will reduce performance.

 

[8350rocks]

No, you have to reduce clock speed too in order to see this benefit...and the OP was clearly not looking to reduce clock speed. Don't give him bad information...

You do not have to reduce clock speed whatsoever. I can run an i5-3570k at stock speeds anywhere from 1.06v to 4.02v (well below stock voltage) before any sort of throttling begins to occur. I'm not giving bad information, I'm giving accurate information.

If you keep the clock multiplier up and reduce the voltage you're going to run hot. It's the same effect that occurs when your PSU goes bad and your components over heat.

This is bad information. Utter BS, and I haven't the slightest idea where you're getting it from - if you stay at stock clocks and undervolt until the CPU begins to throttle, you aren't going to run hot at all, because it's just like overclocking - you're running the chip at the lowest voltage it can use at that clock speed. What you state here is completely wrong.

Additionally your performance will not be the same when you undervolt the CPU.
Don't mislead someone. Yes the CPU uses less voltage if you undervolt it, and it will keep temperatures down under reduced load. At increased load temperature increases because the voltage required to run the CPU at higher load isn't there...

If you could stop accusing me of misleading people, yes, as long as you don't downclock the CPU but only undervolt it, your performance will be exactly the same, because you're running the chip at the same speed.

Also, how in the world would the chip needing more voltage increase heat? What drugs give these ideas - both of you seem to think that, and it's absolutely incorrect. If you aren't giving the chip enough voltage, it won't boot, just like how if you overclock it too far, it won't boot until you give it more voltage.

There is no possible way that undervolting increases heat. If you do it correctly, there is also no possible way that it will reduce performance.

1.) Your voltage numbers are WAY off...because if you put 4.02v to your CPU then you would fry your CPU and likely your mobo considering that safe operating range is up to 1.45V on intel CPUs and up to 1.55v on AMD.

2.) Wrong: http://www.pcmech.com/forum/computer-hardware/31756-why-does-low-voltage-create-high-temperature.html

That's an engineer forum, and the second and third posts explain why you're not accurate.

3.) If you are supplying less voltage to your CPU then the instruction handling capability is lowered, and it will not perform optimally, this will decrease speed and increase heat even if you do not change the clock speed.

 

[DarkSable]

1) That was quite obviously a typo, considering the context of the sentence - it should have been 1.02v. Also, safe operating range for current Intel CPUs is 1.35v at maximum.

2 & 3) [combined] No. It doesn't work that way - like I said, if undervolting is performed correctly, there is no downside. Correctly undervolting involves decreasing the current to the point where the chip still runs.

Consider the scenario of overclocking with an i5-3570k - you increase the voltage until you can run stably at the clock speed you're aiming for. Then you decrease the voltage step by step until you lose stability. The reason you do this is because until you DO lose stability, there is no decrease in performance, so you reduce the voltage to achieve the lowest heat possible.

Undervolting a chip works the EXACT same way, except that instead of aiming for a target clock speed and reducing vcore to the most stable level, you're starting with the clock speed you want already, and then reducing vcore to the least amount which still provides stability.

Now: that forum you linked actually reinforces my point, if you read it closely enough.

When a device is rated at say 2.0 volts and only 1.8 volts is available, many devices will "compensate" by using more current where voltages are lower. This is grossly oversimplified as all devices operate in a differing mannor.

Much of what they're talking about has absolutely nothing to do with a computer. It is, however extremely easy to test. Take your CPU, set it to absolutely stock settings, and run a stress-test benchmark with it, monitoring temperatures.

Undervolt the CPU to just above the point of stability without touching any other settings, and do it again - the difference between benchmarks will be well within the margin of error, and there will not be more heat produced; quite the opposite.




What this is all stemming from is an absolute misunderstanding of how we're defining "undervolting."

You're taking it as attempting to run the chip without sufficient power.

I'm taking it as looking at a chip at stock settings, seeing that it's being given more power than it needs, and cutting back to run it just with sufficient power.


There's a big difference between those two definitions, which is where our disagreement is coming from.

 

[DarkSable]

Little bit more literature for you:

This is a tech review article on why you want to undervolt:
http://www.anandtech.com/show/5763/undervolting-and-overclocking-on-ivy-bridge

This is an enthusiast's guide to undervolting which emphasizes precisely my point - that undervolting is not doing anything but "trimming the fat," so to speak, of the pointless, extra vcore running through a chip.
http://forum.notebookreview.com/hardware-components-aftermarket-upgrades/235824-undervolting-guide.html

 

[8350rocks]

Little bit more literature for you:

This is a tech review article on why you want to undervolt:
http://www.anandtech.com/show/5763/undervolting-and-overclocking-on-ivy-bridge

This is an enthusiast's guide to undervolting which emphasizes precisely my point - that undervolting is not doing anything but "trimming the fat," so to speak, of the pointless, extra vcore running through a chip.
http://forum.notebookreview.com/hardware-components-aftermarket-upgrades/235824-undervolting-guide.html

So, you're only talking backing of a few hundredths...

Ok, well that makes a little more sense...because if you reduce power to something below optimal operating range, then it draws more current and actually creates heat because the mechanical part is trying to compensate for lower voltage...but if you're only making a minor adjustment downward and not dropping below the threshold of normal operating range then I could see where you would dissipate some heat...

However, if you were going to do that, a word of caution, dropping your voltage too low would be as bad as a high voltage overclock because you would start generating heat and drop out of the optimal voltage range, not to mention causing instability in your CPU and likely failure to even get the system to boot.

 

[FlyingHawk08]

Ah thanks guys, really great help for me
The knowledge of undervolting has really set in my mind, I know what to do now to my future cpu thats coming... 😀

 

[8350rocks]

Glad to help...please share some solution love to one of us.

 

[DarkSable]

So, you're only talking backing of a few hundredths...

Ok, well that makes a little more sense...because if you reduce power to something below optimal operating range, then it draws more current and actually creates heat because the mechanical part is trying to compensate for lower voltage...but if you're only making a minor adjustment downward and not dropping below the threshold of normal operating range then I could see where you would dissipate some heat...

However, if you were going to do that, a word of caution, dropping your voltage too low would be as bad as a high voltage overclock because you would start generating heat and drop out of the optimal voltage range, not to mention causing instability in your CPU and likely failure to even get the system to boot.

If you're lucky, more like close to two tenths, but yeah. All I'm talking about is paring back stock voltage (or voltage on an overclock) to the minimum possible for stable operation, not trying to make the chip run without enough voltage.

If one tried that, or dropped voltage too low, generally what happens is you know it, because the system doesn't boot - same thing as if you're overclocking, and don't have enough voltage.

 

[dish_moose]

Common sense - Why would you undervolt to the point where the system does not operate stably or not at all?? 8350 - just understand that there will always be somebody that can teach you something - embrace it. Well done DarkSable for "sticking it out" - you are the only choice for Best Answer because you did not give false info.
-Bruce

 

[YeahPete]

You people are hilarious. I own an 8320.

Guess what happened when I lowered my CPU voltage to 1.1750 V?

My CPU now runs STABLE with NO THROTTLING 20 degrees C COOLER than at the stock voltage of 1.4 & 1.5V my stupid motherboard was throwing at it.

Before I undervolted I was getting throttling and CPU was topping 53 C. (stock cooler) with other temps getting high as well.

I undervolted to 1.750V and now the CPU doesn't get above 42 C at full load with NO CHANGE in cpu speed.

I am tinkering with RAM voltage and after that will lower all the other voltages I can that allow me to run stable at 100% load for 24hrs.

 

[dacquesta1]

lower voltage = less heat

if your trying to run voltage so low that the chip is unstable what does it do? It CRASHES, it doesn't sit there trying to calculate and raising in temperature because there isn't enough voltage. It usually hard locks and then you have to reset and increase vcore.

 

[dish_moose]

I did it! I picked the solution because Dark Sable understands the concept. 8350rock said "f you reduce power to something below optimal operating range, then it draws more current and actually creates heat because the mechanical part is trying to compensate for lower voltage.."
This may be true in a motor - not so much in a cpu. Undervolting possibly allows you to run the cpu at the same frequency but at lower voltages - this means less heat. Heat generated in cmos circuits is a function of voltage and frequency. Because not all cpus are exactly equal, the manufacturer will specify enough voltage for the all of the devices that pass QC to work. If you get lucky, your cpu will OC better or possibly work the same with less voltage. The OP wantted less heat - therefore undervolting can be a great thing.
-Bruce

 

[DarkSable]

Well thanks, Dish_Moose, 'preciate it.

I had forgotten about this thread - the number of times I've butted heads with 8350rocks...

Good point about the motor, though - hadn't thought about that side of things.

 

[kplusalot]

I just thought I would throw in my 2 cents. I'm no mathematician, but the last time I learned math, 125w-95w was 30w, not 40w. I do agree that it would only be a few dollars though.
365day/yr * 24hour/day * 30w * 1kw/1000w = 262.8kw*hour/yr
At a moderate $0.11 per kwhr, that's about $29: less than $2.50 per month or less than half of a Mc Donald's value meal.

If you are undervolting, the only reason to do it is to lower the TDP of the CPU. Otherwise, it's not worth your time to find a stable voltage/clock speed medium. If you're really worried about power, save some time and money and just get the 95w/3.3ghz 8300 instead of the 125w/3.5ghz 8320.

UPDATE: If you are worried about overloading your breaker or PSU, it's a non-issue. The 30w would add about 1/4 of an amp on your 120v line, and it's the 12v rails on your PSU that usually get overloaded. The CPU doesn't use the 12v rail. If you are using a 95w motherboard, I highly recommend you purchase a CPU that is intended for 95w or less.

 

[ergohack]

Sorry about the necropost, but I needed to correct this when I saw it.

The CPU doesn't use the 12v rail.

Wrong, the cpu most definitely uses the 12v rail. That 4pin/8pin connector almost every motherboard needs? Dedicated 12v, on top of what the 24/20 pin connector already provides. If you have a PSU that has coloured wires, just look for the yellow ones, they are almost always 12v.

There was a time when CPU's used the 5v rail, but that was over a decade ago.

 

[keimo999]

I'v got a 8320 and my ''sweet spot'' is 4.1Ghz and 1.2 volts stable. stock it was ~3.9Ghz and 1.24 volts and i get around same temps (The way I understand is that 8320 only boost to that 3.9Ghz on all cores and to 4Ghz on only one core if the rest aren't on high load).
Going to 4.2Ghz requires ~1.256 volts.
Thouht just to put this here.