Different fan speeds in SLI.

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Kizenco

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Mar 13, 2013
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10,510
Hi,

I'm currently having a temperature problem with my top card. I've done my research and I will do a few things to get it down. What I'm wondering however, if somebody knows, my top card's fan is slower than my bottom card.
I thought the logic was that the card with the highest temperature would have the highest fan RPM.

I have to Gigabyte GTX 570's in SLI. The top card is about 50C idle and the bottom card is around 35C. When the fan speed of the GPU's is on 40%, the top card fan runs unstable from 300-550 RPM. And that's quite slow. The bottom card fan runs stable on 1980 RPM. Why is that so? They're both on 40% GPU fan speed, but shouldn't the top card have the highest fan speed?

I'm checking all this in MSI Afterburner. I have the newest drivers from nvidia 314.14
I'll provide any other information that's necessary. While it's not that important as I think I'll be able to fix the temp problems, I'm still curious if something is wrong. I'm suspecting this has something to do with the air flow. And the cards are almost literally on top of each other, so there's very little space between them. But still, I don't think the bottom card should be having fans running that much faster.

CPU: i7-2600k
Motherboard: Gigabyte P67A-UD7-B3
RAM: Corsair Vengeance DDR3 8GB
PSU: Corsair Gold AX 850W
GPU: 2x Gigabyte GTX 570
 
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bystander

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Dec 9, 2009
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Are they the same model cards? The bios on the cards might have different fan profiles, and possibly different fans all together which would work at different speeds.

If they are different, a fan profile in MSI Afterburner may have poor results. Some aftermarket HSF's need to operate at higher fan speeds.

The reason one card keeps changing speeds is because the temp is constantly passing a threshold that kicks the fan speed higher, once higher, the temp then drops below the threshold and drops to the lower speed allowing the temp to increase and continue the cycle.

One last question, do you have more than one monitor hooked up? That would explain the 50C idle temp on the top card, as multiple monitors causes the primary card to run about 10-15C hotter. It may also be a lack of space between the cards causing issues. Airflow is important to keep cards cool.
 
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K

Kizenco

Honorable
Mar 13, 2013
3
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10,510
Thanks for such a quick response. They are both of the same model, I ordered two of the same card. What I'm wondering though is that when I'm putting both cards on max fan percentage, the bottom card is able to achieve much higher speeds, why is that? Should it be like that?

I have only one monitor. I think I have bad airflow in my cabinet, but I'm not totally sure about how to fix it as I have one rear fan, two top fans, one in the front and one on the side. I have the Cooler Master HAF X Full Tower case.
However, what I'm going to do in order to decrease temperature is probably moving the bottom card one slot down, which means using the PCIe x8 instead of the PCIe x16. I've read that it doesn't really affect the performance by that much and I think it would only benefit as the top card is performing worse when at high temperatures.
 
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bystander

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Dec 9, 2009
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I do the same. I moved my 2nd 680 down a slot and it runs at x8 instead of x16. As long as it isn't x4, it runs well. The temp difference is HUGE, and makes the system more stable. That alone may improve results a lot, but keep in mind, not every chip is as good as the next for OCing. Some just OC better than others. While most 680's will top out at 1250 on stock voltage, some do better and some do worse. I just learned that my RMA'ed 680 is about 50mhz lower than the one I had replaced. That is just the luck of the draw. Though now that I use PrecisionX, voltage increases are possibly able to over come that limitation.
 
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K

Kizenco

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Mar 13, 2013
3
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10,510
I'm not planning on overclocking my cards though. Depends what kind of temperature I will get when I move the bottom card lower. I do believe it will cause a massive change in the temperature and I'm also interested if the fan speed of the top card will go up when it'll get more space.
 
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