GPU fan noise in Crossfire

[knight_40k]

I recently CF my 4870 and notice the fan noise has increased drastically. In my systems as single cards the noise was fine and what I would call normal. They are both Asus 4870 1G Dark Knights and in an Asus Crosshair V mobo now. Neither of the cards were OC'd in their previous systems. When I decided to make them CF I placed the new card in the extra slot, attached the CF bridge and did a fresh install of Win7. Is my mobo default OC'ing them? I have nothing installed on that PC except basic mobo drivers and the latest Radeon driver. Also note the top card which I have my monitor plugged in to seems to run hotter while the other card is much cooler. Is this normal? Both cards work just fine as single cards but some how they have increased the fan noise while being in CF. The location of the case is in an open space, lots of air flow and they are in Antec DF30 case. My PSU is corsair TX750 V2 which also has a large fan.

please help.

 

[killersquirel11]

How much space between the cards? Might be worth pointing a case fan at the gap and see if it helps...

 

[HugoStiglitz]

no the mobo won't be auto OC'ing them

try ising software to monitor the temperature (sapphire trixx) and see if its just the fan speed increasing or temperature as well.

monitor without CFX enbabled and then with it enabled.

 

[photonboy]

Fan speed is controlled completely by the graphics card by default.

If they work individually, then they're still working properly in Crossfire.

I suspect the added noise is due to the added HEAT with two cards inside the case, especially if one of the cards has restricted cool air flow and needs to speed up to compensate.

 

[knight_40k]

Fan speed is controlled completely by the graphics card by default.

If they work individually, then they're still working properly in Crossfire.

I suspect the added noise is due to the added HEAT with two cards inside the case, especially if one of the cards has restricted cool air flow and needs to speed up to compensate.

So if one card is heating up and increases fan, the other does the same?

The one card is located below the CPU as standard in most mobos, the other may be slightly obstructed airflow. It is in the 3rd PCI slot (covering the 4th) above the PSU with less than an inch of space between the psu fan and gpu heatsink. The amount of space between the two cards however is quite a large gap. I do have an optional fan slot on the side panel of my case, would that help? The odd thing is, the card directly above the PSU is the one that is cooler even with the more limited airspace.

 

[killersquirel11]

I'd give the optional side slot a shot and see how it goes. Some extra air flowing in to the case there certainly [strike]wouldn't [/strike] shouldn't hurt...