Computer crashes with three graphics running at the same time despite 1200w PSU

[ande85]

For whatever reason my computer crashes when I have three cards running at once. With three the computer will cut off automatically after about 10-15 minutes, and with two cards running, and one sitting idle, the computer will completely freeze up in about an hour. Is there anything I can do to fix this? The only fix I've found is to unplug one of the three cards, then two can run just fine.

This is the power supply I'm using. It should be able to handle the job since, with three cards running, only 950w is being used up, which leaves over 200w of overhead. Also, as for the RAM, I ran a memory test on it at advanced settings...nothing came up, so the RAM isn't the issue.

[zvs]

this should be in the hardware forum i think, but

i don't see the power supply?

if it's some cheap generic pos and your cards by themselves are using 950 watts, then you best have ubuntu on a usb stick or something

[ande85]

The PSU is made by OCZ, and is a Power & Cooling Silencer Mk III Series. Here's a link to the specs in question.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817703037

Since the PSU has a platnium rating I figure it muss be high quality...pity it's not muli-rail, but then again, buyer's remorse.

[QuantumKiwi]

Something is heating up and the bios may be cutting the system to save damage.

Have you checked the bios temp settings?

What model motherboard?

[pvtbrutus]

i would try another brand PSU like Corsair. I work in a computershop and OCZ is not a brand we love to sell. Actually we stopped selling it because of the many quality issues.

Also only the wattage says nothing, you have to look at the amperage per rail. A good PSU has one 12v rail with high amperage. Usually a good PSU can deliver all the mentioned watts on the 12v rail alone. Plus the good ones have overcapacity and can go beyond the mentioned max wattage.

[ande85]

y motherboard is a p8z77-v Premium. May be heat...the two 7950 cards were running, and while they were, I touched the heatsink on the side of the 7970, and it was hot to the touch...and it not even running. Maybe heating issues? Maybe something else. The motherboard temperature is 44C (note: I only have two cards in the system now, since this way I get 975 KH/s, compared to only 750 KH/s...I'm mining feathercoins ATM).

Pvtbrutus: What is the amperage of the current PSU I'm using? I can't find it anywhere on Newegg's site, but I do know this PSU was recommended by JohnnyGuru.

[pvtbrutus]

Pvtbrutus: What is the amperage of the current PSU I'm using? I can't find it anywhere on Newegg's site, but I do know this PSU was recommended by JohnnyGuru.

Its mentioned on newegg under details:
+3.3V@20A, +5V@20A, +12V@99.5A, -12V@0.5A, +5VSB@2.5A

This means it has one 12volt rail which can provide 99.5 amps. 12 x 99.5 = 1194watt. This falls in the "good psu" category. However i would still recommend trying a different PSU if possible  to rule out a quality issue.

[ande85]

Might be a heat issue. The case is well ventilated, and has more than it's share of fans, (top, side, rear, hard drive, CPU (obviously), etc.) but as mentioned, if an unused card if hot to the touch, some serious heat is being generated. A liquid cooled system wouldn't work because, well, with three cards sandwiched into one another where would the cooling blocks go? How exactly do people run three or four powerful cards at once without the heat being a factor? There is a way to do it...I'm just not sure what it is.

[SirMintALot]

Use a horizontal case (like Coolermaster HAF XB), not a vertical tower case. Or try watercooling your cards.