New System Builder Crossfire 4870: Heat Problem!

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Hello everyone, I just got a new homebuilt system up and running today and am having an issue trying to set up Crossfire with two identical Sapphire Radeon HD 4870 cards. I have an Asus P6T SE motherboard which puts the two video cards essentially on top of each other--one of them has its cooling fan less than a centimeter away from the other one's underside. In Catalyst Control Center I am showing a 46 degree C idle on the lower card, and a 78 degree C idle on the upper! Under load conditions the hotter card goes above 90 degrees C.

Will this damage the second card? I plugged my monitor into the lower card, thinking that might help take the load off the hotter upper card, but all that seemed to do was make it so I didn't see my own BIOS load-up screen on startup, as I think the motherboard defaults the upper card as the 'primary'. What can I do about this heat problem? I'd be willing to buy an aftermarket cooler but there is very little clearance between the cards and I'd rather get something that vents heat out the back of the case like the stock cooler rather than into the case. I'm not sure what to do. Will these conditions damage the upper card?







SYSTEM:
Asus P6t SE mobo
Intel Core i7 920 2.66 GHz
6 GB corsair ram
2 x Sapphire Radeon HD 4870 cards
Corsair 750TX power supply

 

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Sorry, didn't mean to post this twice, browser problem!

 

[hunter315]

90 is considered hot but not dangerous. In the 5870 review the cards did not heat throttle until 100C. GPUs can sustain much higher temperatures than CPU's due to their different manufacturing processes. You can improve airflow in your case, or add a fan to the side panel that will blow onto the cards and keep them both cooler, either one should drop your temps a bit.

 

[jay2tall]

I had the same issue with (2) Asus 4870 Dark Knight cards. The top card would top out at about 100C in Crysis. This was on an Asus P6T board. I ended up selling both for a 5870. Best choice i made. I took a hit selling them on ebay though. You can always try and get a 120mm fan and blow it over the back of the cards, mainly the top card. What happens is heat from the bottom card raises up over the top card which now has no fresh cool air to cool with. So basically the bottom card heats the top card. You need to move air over the two cards.

 

[collapsitar]

Fair enough, I'll head to the store and see if I can pick up a 120 or 140 mm fan tomorrow. Hopefully that will make a bit of a difference! I neglected to mention those numbers were with my fans running at 100%, pretty loud. So Hunter315, you think the top card idling at 78C idle over time shouldn't damage it?

Just one other question. Does it matter at all in terms of card heat loading which card of the two I plug my monitor into? I have it plugged into the bottom (cooler) card right now to try and take load off the hotter top one, but I don't think it is the 'default' because when I boot my system I don't see the BIOS unless I am plugged into the top card. Can I run the signal out of the top card without contributing to my heat loading; or alternately, can I somehow change which card is recognized as the 'master' so I can see the BIOS loading screen running out of the bottom card?

 

[JackNaylorPE]

The 4870x 2 hts 98 in an enthusiasts case so the temp shouldn't fry the card. However heat reduces life of every component, so cooler is always better. A nice big case with lots of air flow (HAF 932 / Antec 1200) would do wonders.

 

[jay2tall]

^
Video cards are made to take the heat, but when they climb to 100C you run into issues. 90C isn't that bad for a card under load in Crossfire. I think if you point a fan over it, that will help alot to move air.

You should plug into the primary card, they are sharing the workload so it won't make a difference.

 

[JofaMang]

Ouch, 2 4870 fans at 100% would be really wooshy. You will probably see a healthy drop in temps if you add a side fan to blow on them, especially if you have some good exhaust pressure pulling air out elsewhere. If you already have good pressure coming in, try the side fan as an exhaust instead. I had heat problems with my 4870 before I added a side fan, blowing in helped, but bumped my CPU temps significantly. Exhaust helped even more, and brought my CPU temps back down to earth.