2 same 5970 card, 20degree difference, what the?

[newguy05]

See below screenshot, it makes no sense.  And i clocked the 2x lower temp gpu to 850mhz and they still run 20degree cooler than the other 2x gpu. Why? how could this happen?  I have both card installed right next to each other in a 2xpcie slot asrock am3 cheap mobo.

I know the card with the fan blocked by the 2nd card will run hotter, but it still doesnt make sense to be 20 degree hotter.

Anyone know why this is happening?  

[fascistmuffin]

What's the GPU activity looking like for card #1? 61C is very very low for a 100% load GPU. Or it's possible the temp sensor is malfunctioning.

[newguy05]

All 4 gpu are 98-100% load and stable using the clock speed in the screenshot. The two that I clocked to 850mhz is getting around 350 mhash each, the while the other 2 90degree gpu is generating 280-300 mhash with the lower clock speed.

Are you saying the temp sensor malfunctioned on the lower temp card?  Or could having the fan not getting blocked really make that much difference? 

Can anyone else with similar setup offer some insight? thanks

[fascistmuffin]

How are the GPU numbers correlated to the dual GPU on the cards? Is GPU 1 and GPU 2 on the same card?

[petercyr]

How are they setup in the case? Any space between them? I find even with an inch between two cards, the top one runs about 10c - 14c hotter.

[hennessy]

I had the same issues running four cards. It's simply because the second card gets all the warm air from the cards right next to it. I solved it by slightly bending each card a little to get a bigger gap between them and I put a 12cm fan right on top of the gaps. Reduced overall temperature by about 10 degrees C and the hottest card is now on line with all other cards, maybe 4 °C more. That of course requires a non-case setup. I'll make some pictures as soon as I get to our "mining place"

[Jack of Diamonds]

Same thing happens with my 6990's.

I can even overclock the second core to about 900mhz and it still stays pretty cool.

The primary core gets up to 85-92c even at stock frequency, and is always 10-12c hotter than the other core no matter what I do (even 100% fan speed, no other cards attached, etc.)

[padrino]

You say the fan is "blocked", I assume they are directly mounted to a motherboard next to each other. If that is the case the numbers you are showing are not surprising at all.

[newguy05]

yeah this sucks, i am not sure what to do now.  Only option is to get a new mobo with the pcie slot that are further apart to have some gap between the cards.   I am running with 1 gpu on the 2nd hotter card and it is now at 75degree, but as soon as I turn on its 2nd gpu, the thing goes to 100...

the first card I have both gpu clocked at 850mhz with no problem.  nuts!

[melmo]

I think a pci-e extender will help you out and be a lot cheaper than a new motherboard.  In the meantime, try wedging something between the cards and put a fan right on top of them.

[newguy05]

What do you guys think about putting one of those directly behind the gfx cards? right at their butt!   Will that help with cooling?

[Meatball]

I get the same thing on my rigs that have the 4 cards all up against each other.  The two cards that are the 'interior' cards are always running 10+ degrees hotter than the cards that have one side not up against another card.  Putting a fan behind them helps drop it a bit, so give that a shot, but don't spend a ton of money.  I found this fan at my local Lowe's for like $12 and it works great.  Just the right size to blow air through all four cards and sits just about the right height for your cards if the motherboard is laying flat.

The other option is to separate them by pulling them off the motherboard with extenders.   If you don't want to pull the cards out, just make sure there is as much space between the cards as you can get, but be very careful 'bending' them against the slots. 

[hennessy]

Depending on the Graphic card layout, it's not always the best to put the fan behind the cards. If your cards have a "tunneling" system where the whole fan and cooler are sealed off and only the two sides are open, put the fan inside the case to blow into the cards.
If the cards are more open like mine, the card will get it's fresh air from above the card and blow air into both directions. If you place a fan on one of the venting sides, the air flow will stop somewhere and heat up. It's better to place the fan on top then.