My 850W PSU is not Enough for Two GTX 480 Stressed by EVGA OC Scanner



EVGA OC Scanner and GTX 480 SLI
Just before the PSU shutdown 😉 – SLI visual indicator enabled…



I took the time this morning to test a 2-way SLI of GTX 480. For two reasons:

  • 1 – because it’s a geeky stuff 😀
  • 2 – to test the new SLI profile that has been added by NVIDIA in the R257.15 for EVGA OC Scanner.

The cool thing with EVGA OC Scanner is that it has now a SLI profile in latest NVIDIA drivers. No longer need to rename the exe in etqw.exe (you can even use that SLI profile for FurMark 😉 ). If you have a SLI system, just run the OC Scanner in fullscreen (fullscreen mode is fundamental for SLI) and you’re okay!

That’s what I did… 1920×1080 fullscreen with the power draw unlocked… and I got a nice shutdown after one second.

Hummm… I don’t know why but I was sure that my PSU was the weakest link of my testbed (CPU = Core i7 960). This kind of shutdown is symptomatic of a too high power consumption. I thought my 850-watt PSU was enough to feed my testbed but I was wrong.

Antec TPQ 850W PSU
my Antec TPQ 850W PSU

That’s why I added in the OC Scanner a way to control the power draw via a simple delay in the rendering loop (I called it tone down delay). By default the tone down delay is equal to zero. If you increase the value, let’s say tone down delay = 20, the rendering is stopped during 20 ms. And you can increase or decrease the tone down delay as you want.

The tone down delay has allowed me to confirm that my PSU was not enough powerful to feed two highly stressed GTX 480. I started EVGA OC Scanner in 1920×1080 (power draw unclocked) with a tone down delay of 50ms and I decreased it until I reached the PSU shutdown (the shutdown occurred for a delay lesser than 16ms).

Conclusion: you must have a 1000W or better a 1200W PSU for enjoying a 2-way SLI of GTX 480! I hope I’ll able to check that assumption shortly…

This tone down delay will be available in MSI Kombustor too…



13 thoughts on “My 850W PSU is not Enough for Two GTX 480 Stressed by EVGA OC Scanner”

  1. Pingback: 850W PSU is not Enough for Two GTX 480 Stressed by EVGA OC Scanner - CHIP Forum

  2. Tyler

    This generation of graphics cards are fucking our environment in the ass. Such a high power consumption is simply unacceptable in my books, as for the most part, electricity is not generated from renewable resources and most nonrenewable sources are polluting our environment like crazy. As much as I love these stuff, I will never buy a computer component with such a high power consumption. This is what happens when manufacturers don’t have the technology to move to shrink the die. And the irony in that is that there absolutely no single game that requires such a crazy setup. Seriously, what the fuck is going on? Oh, I know, the law of diminishing marginal returns has kicked in.

  3. Tyler

    Correction:
    …This is what happens when manufacturers don’t have the technology to shrink the die…

  4. Lightness1024

    Pollution is true for US and others.
    But in france the production is 80% nuclear, 10% waterfalls, and 10% of others incl. 2% of wind.

    I’m more worried about the chemical process needed to create the ASICS and the PCBS.

  5. Lightness1024

    Also, I wanted to add that Antec is not the best manufacturer for power supplies. And that if you measure your consumtion with ampermetric hall effect claw, you’ll see that you’re probably far from 800W.
    (fortunately protections trigger before overload)

    eat Seasonic :)

  6. Fool Gamer

    850w not enough how about my mine 530w
    ha ha ha ha
    enough for my 5850

  7. DJ

    Can’t believe that you thought a 850 would be enough. A bit of research would have told you that. Plus, it’s not just about wattage or even amps but the quality of the PSU. Antec really doesn’t make very good power suplies. There’s a reason why NVIDIA does SLI certification and it’s not just for marketing.

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  10. landogimps

    A few thoughts:

    The picture shows that psu has several rails at 25A each. Those cards reccomend 42A on a SINGLE rail. I have the previous version of that PSU running 8800gts’s and have major problems (18A rails w/ 22A cards)

    From what I can tell, the psu is designed with 1 rail for each video connector. Definitely not good. I have also heard of people having issues with that specific psu if they plug two video cards into the same colored plug (black, black or red,red). Their problems were fixed by alternating the plugs.

  11. Pingback: [Test] Corsair AX1200 PSU And Two Highly Stressed GTX 480 in SLI - 3D Tech News, Pixel Hacking, Data Visualization and 3D Programming - Geeks3D.com

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