Massive Difference in PSU Calculators

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jestervae

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May 16, 2011
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Greetings. My PC is a bit old, handbuilt in 2011 and it has been wonderful. Recently, I checked some benchmark tests and decided it was time to upgrade my GPU. It is absolutely the weakest link. I'm currently using a RADEON HD 6770, which wasn't even high-end in 2011.

Being thrifty, I decided on a RADEON R9 270x because it's reasonably-priced and rates quite well. However, it seems my 500W PSU isn't beefy enough to handle it, though the GPU calls for 300W dedicated.

So, I checked some different PSU calculators to see what I'd need to run it. CoolerMaster and eXtreme both said just over 400W, which should be fine for me. However, NewEgg's calculator says I need over 900W, which seems a little absurd. Here's what I've got:

Intel Core i5 2500 (3.30Ghz)
500Gb HDD 7200 RPM
8Gb DDR3 RAM
P67-PRO MoBo
1 Combo CD-RW/BluRay drive

It seems to me that 400W is a bit low, especially for startup, but 900W seems awfully high because it suggests that 600W are needed for components that I'm already running with just 500W. Am I missing something?
 
Solution
JackNaylorPE
1. If ya wanna use a calculator avoid ones that have a vested interest in selling you something bigger (that costs more money). This on eowrks fairly well as long as you remember to include capacitor aging ..... 10% for Seasonic X series .... and maybe 30% for Corsair CX.

http://extreme.outervision.com/psucalculatorlite.jsp

2. Have someone else do the work for you.... Guru3D does a nice power consumption analysis. So if you do a Yahoo / Google search on "Guru3D [insert your card name here]" , you will get an answer that works on 98% of builds

http://www.guru3d.com/articles_pages/msi_radeon_r9_270x_gaming_review,8.html

This is Guru3D's generic power supply recommendation for the R7 and R9 series:

AMD R9 270X - On...
Click to expand...
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Gam3r01

Gam3r01

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Jan 12, 2013
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None of them are correct. There are very few that are actually close, pcpartpicker does alright on it.
Some, like newegg, take the "recommended" wattages which are well over what the cards actually draw.

Watts arent the only thing that need to be taken into consideration, look at the amperage on the 12v rails.
 
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JackNaylorPE

JackNaylorPE

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Oct 30, 2004
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1. If ya wanna use a calculator avoid ones that have a vested interest in selling you something bigger (that costs more money). This on eowrks fairly well as long as you remember to include capacitor aging ..... 10% for Seasonic X series .... and maybe 30% for Corsair CX.

http://extreme.outervision.com/psucalculatorlite.jsp

2. Have someone else do the work for you.... Guru3D does a nice power consumption analysis. So if you do a Yahoo / Google search on "Guru3D [insert your card name here]" , you will get an answer that works on 98% of builds

http://www.guru3d.com/articles_pages/msi_radeon_r9_270x_gaming_review,8.html

This is Guru3D's generic power supply recommendation for the R7 and R9 series:

AMD R9 270X - On your average system the card requires you to have a 500 Watt power supply unit.
AMD R9 270X Crossfire - On your average system the cards require you to have a 700 Watt power supply unit as minimum.

If you are going to overclock GPU or processor, then we do recommend you purchase something with some more stamina.
Click to expand...

As you can see on the link ....

GPU power consumption = ~ 177 Watts
Click to expand...

With the 270x still hovering about $170
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127794

..... the 760 would have to come down to $200 to be equivalent on a price / performance ratio ... and I don't see that happening for at least 2 weeks

The 760 draws less power (GPU power consumption = ~ 169 Watts) and gives about 12% more performance but enough to change the PSU size recommendation

Here is Guru3Ds power supply recommendation:

GeForce GTX 760 - On your average system the card requires you to have a 550 Watt power supply unit.
GeForce GTX 760 SLI - On your average system the card requires you to have a 700 Watt power supply unit.

If you are going to overclock GPU or processor, then we do recommend you purchase something with a bit more stamina.
Click to expand...

keep in mind also that their test system includes "Our test system is based on a power hungry six-core Intel Core i7-3960X Extreme Edition Sandy Bridge-E based setup on the X79 chipset platform. This setup is overclocked to 4.60 GHz on all cores. " ..... so that can be as much as 90 watts or so more than a Haswell CPU.

I can only surmise that the PSU bump for the 760 even tho it draws less power is due to the fact that R9 boards ae already pretty close to max OC in the box whereas the 760 has a lot more headroom

In the end, the 500 watt PSU, assuming it's a quality unit and hasn't suffered too much capacitor aging (Japanese caps hopefully) , should do ya fine.
 
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Solution
J

jestervae

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May 16, 2011
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I'm guessing capacitor aging is at fault here. After 3 years of heavy use, there's a chance (from my research) that my PSU is working at about 50% of its initial wattage. My current setup calls for around 300W, so it's clearly time I upgrade the PSU regardless.

Thanks for the great info. eXtreme says I should have 401W for the R9 build. I'm going to take the advice given here and get the XFX 550 just to be on the safe side.
 
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