PSU Overload or ineffective fan?

PSUs: The source of DC power for all components in the PC & often a big noise source.

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Listetyven
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PSU Overload or ineffective fan?

Post by Listetyven » Fri Feb 01, 2013 4:49 am

I recently installed a new graphics card, HD7950, and ever since the fan in PSU has really been going fast when using demanding graphics.

My Computer:

Corsair VX550 550w
XFX HD7950 DD
Intel i5 3450 @ 3.1 GHz
Asrock H77 pro4 MVP
4x4 Gb Corsair Vengeance RAM
3x SATA HDD, 1x SSD
3x 120mm Loud AnnoyingFans®

My former GPU was a 9800GTX+, and it didn't make the PSU work as this new card does. Sure the HD7950 has a 40w higher TDP than 9800GTX+, but it generates less heat.

When i start a game, the PSU fan reaches a plateau than sounds like 2500-3000 RPM within one minute, but it doesn't seem to generate that much heat.

I recently took it apart to clean out the dust, but i am going to do that again today.
So my question is; should i go buy a highly effective fan and replace it or am i putting too much load on this here PSU? (i am poor, so i would like it not to be the latter :) )

Thanks in advance and great forum BTW!

edh
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Location: UK

Re: PSU Overload or ineffective fan?

Post by edh » Fri Feb 01, 2013 5:38 am

Listetyven wrote:My former GPU was a 9800GTX+, and it didn't make the PSU work as this new card does. Sure the HD7950 has a 40w higher TDP than 9800GTX+, but it generates less heat.
Not quite. Your new card has a 40W higher TDP and therefore does output more heat. Energy can neither by created nor destroyed and all forms of energy end up as heat through one way or another. How do you think it doesn' output more heat? Does the card not run as hot? Temperature is not the same as heat, it is a heat density and does not reflect power directly as there are all kinds of ways the heat could be being dissipated.

The speed up in PSU fan will most likely be caused by the higher power draw on the PSU and hence heat generated in the PSU, not the graphics card directly. Replacing the fan on the PSU is unlikely to make much difference as you still need to cool that PSU. Most likely you have quite a high sound level anyway given the number of HDDs and fans.

The Corsair VX series is quite old now and it would be expected that as it is not as high efficiency as more modern PSUs, it will waste more energy as heat under higher loads and hence there is mroe cooling requirement for it.

If you have not already done so then a good way of improving the existing PSU without spending money would be to open it up, clean it out and remove the grill from the fan. This might give you a slight audible improvement. Beyond this a new PSU may be the best solution given you have quite a high power requirement.

Spoon Boy
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Re: PSU Overload or ineffective fan?

Post by Spoon Boy » Fri Feb 01, 2013 6:27 am

I done a quick work through on this http://www.extreme.outervision.com/PSUEngine PSU calculator and it seems you are pushing close to the max load on you PSU, i came up with 445W.
But IDK if i got all your components so you may want to give it a try your self.

edh
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Re: PSU Overload or ineffective fan?

Post by edh » Fri Feb 01, 2013 6:56 am

Spoon Boy wrote:I done a quick work through on this http://www.extreme.outervision.com/PSUEngine PSU calculator and it seems you are pushing close to the max load on you PSU, i came up with 445W.
Be wary of these numbers. This does not give you the TDP and massively overestimates. My 150W system is put at 250W by that calculator.

300-350W is a more likely number for this systems actual TDP. A 550W PSU is plenty but you have to accept that drawing that much power through a PSU with 80% efficiency is going to result in perhaps 80W of heat in the PSU to be got rid of, hence the fan noise. It may be that with the graphics card upgrade has pushed it beyond a 50% point and caused the fan to ramp up massively. You either have to reduce your power consumption or replace the PSU if you really want silent.

Listetyven
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Re: PSU Overload or ineffective fan?

Post by Listetyven » Fri Feb 01, 2013 7:23 am

I also came up with 445 - 450w with a PSU calculator. So i guess i can't expect to achieve quiet opration... Thanks a lot for the answers, it pretty much clarifies the situation for me :) Now i am thinking about an intake from my wall cavity.. it's cold out there between the bricks :P

CA_Steve
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Re: PSU Overload or ineffective fan?

Post by CA_Steve » Fri Feb 01, 2013 7:31 am

Your stressed load power is < 350W..and probably < 275W while gaming. A lot of PSUs start to crank up the fan rpm past 50% load...it could be your PSU is running hotter (clogged up fan blades, poor airflow) causing an earlier fan ramp.

Spoon Boy
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Re: PSU Overload or ineffective fan?

Post by Spoon Boy » Fri Feb 01, 2013 9:34 am

CA_Steve wrote:Your stressed load power is < 350W..and probably < 275W while gaming. A lot of PSUs start to crank up the fan rpm past 50% load...it could be your PSU is running hotter (clogged up fan blades, poor airflow) causing an earlier fan ramp.
Not that im questioning the stressed load is under 350W, but as us layman's don't know enough about PSU is there a better way than using something like a calculator to work out what load our PSU's are under.
Without buying a load tester or other expensive equipment, or when your planning a system build and cant test things directly.

Its more than likely all PSU calculators over egg the results to air on the side of safety, but is there a better way to get a more accurate result ?

edh
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Re: PSU Overload or ineffective fan?

Post by edh » Fri Feb 01, 2013 9:50 am

Spoon Boy wrote:Not that im questioning the stressed load is under 350W, but as us layman's don't know enough about PSU is there a better way than using something like a calculator to work out what load our PSU's are under.
Well if you look at manufacturers data you will find TDP. For things like CPU and graphics card this stuff is pretty easy to find and is the majority of the load for most systems. Other components aren't very high power consumption but can be added up to the nearest 5, 10, 15W per component.
Spoon Boy wrote:Without buying a load tester or other expensive equipment
Load testers are cheap equipment. Mine was £12.49 from Maplin some years ago. This is a tiny amount compared to the difference between a sensibly sized PSU and how much some people waste buying a 1500W PSU. I also find it invaluable for other electrical equipment, for example measuring the power consumption of fridges and making a financial case for replacement with a newer, more efficient model based upon electricty prices. Amazing how many consumers are happy to buy things on efficiency promises without even doing the calculations themselves, it counts for cars too. :roll:

Looking at power measurements on SPCR and other sites does give you some more idea but remember to distinguish between DC and AC. PSUs output DC power so this is the rating that matters for the PSU. AC measurement is useful for efficiency measurements and costs and is the most popular measurement as it is easier to make, all you need to do is convert back to DC to see component loads.

xan_user
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Re: PSU Overload or ineffective fan?

Post by xan_user » Fri Feb 01, 2013 10:27 am

does your mobo report psu voltage info to the os? try a program like speedfan or hwmonitor ect and see what the various power rails do under different loads.

http://www.tomshardware.com/forum/29025 ... -stability

Spoon Boy
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Re: PSU Overload or ineffective fan?

Post by Spoon Boy » Fri Feb 01, 2013 11:41 am

Thanks edh :)
TDP is the most accurate way to work it out and now you have explained it i feel like a fool for not realising it :lol:

So are PSU calculators any good at all maybe just for a ball park figure ?

Ive always been nervous electrickery :shock:

edh
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Re: PSU Overload or ineffective fan?

Post by edh » Fri Feb 01, 2013 12:37 pm

Spoon Boy wrote:So are PSU calculators any good at all maybe just for a ball park figure ?
They're there to sell bigger PSUs than people need. Why else would PSU manufacturers have them on their sites? In addition you'll then get the wannabe overclockers who will read that number and double it 'just to be safe'. This is how 1500W PSUs get sold.

Listetyven
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Re: PSU Overload or ineffective fan?

Post by Listetyven » Fri Feb 01, 2013 12:47 pm

xan_user wrote:does your mobo report psu voltage info to the os? try a program like speedfan or hwmonitor ect and see what the various power rails do under different loads.

http://www.tomshardware.com/forum/29025 ... -stability

I am indeed using speedfan, but i don't what the acceptable margin for voltage variations are.

Edit: I see that you already included a link answering that question.

Spoon Boy
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Re: PSU Overload or ineffective fan?

Post by Spoon Boy » Sat Feb 02, 2013 1:41 am

edh wrote:They're there to sell bigger PSUs than people need. Why else would PSU manufacturers have them on their sites? In addition you'll then get the wannabe overclockers who will read that number and double it 'just to be safe'. This is how 1500W PSUs get sold.
But when the calculator isn't on a manufactures web site ? AFAIK the link i posted isn't affiliated with any manufacturer.

edh
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Re: PSU Overload or ineffective fan?

Post by edh » Sat Feb 02, 2013 2:37 am

Spoon Boy wrote:But when the calculator isn't on a manufactures web site ? AFAIK the link i posted isn't affiliated with any manufacturer.
Outervision make a system which is used by pretty much every manufacturer which offers a PSU calulcator on their website. It's the same one and even if they aren't getting revenue directly from you using their system, they made the system to get revenue from PSU manufacturers.

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