HD7950 Crossfire Issue

tpidner17

Honorable
Oct 28, 2013
4
0
10,510
I have two Radeon HD 7950's in crossfire, a reference design HIS model that I bought near launch day, and a Gigabyte Windforce model i bought last winter. The issue that I am having is with the core clock on the Windforce card. When I put it in the GPU 2 slot (below the HIS card), the core clock constantly fluctuates under load between about 900 mhz (below the base clock) and 1100 mhz (the clock I have set in afterburner), however, when I have the windforce card in the GPU 1 slot and the HIS card in the GPU 2 slot, this does not happen, and the clocks on both cards stay constant at their set values. The reason that I want to switch the cards is because I am getting very high temperatures (~89 degrees) on the windforce card in game when it is the top card, and I have heard that the reference cooler performs better directly above another card in crossfire.

Is this an issue of using mismatched cards, or is something else amiss?
 
Solution
Your motherboard specs would be beneficial in solving your problem. But generally in a 2 GPU setup, the faster card will be downclocked to the speeds of the slower GPU.

tpidner17

Honorable
Oct 28, 2013
4
0
10,510


Oops, sorry, forgot my system specs.
Mobo: Asus P8 z68-v pro gen3
Cpu: intel 2500k at 4.6 ghz 1.38v
PSU: Corsair CX750M

Also, I have just tested the card in the GPU2 slot on its own and it exhibits the same behaviour (non-crossfire). And downclocking isn't an issue, as the two gpu's are both clocked the same in crossfire (how I have them set up at least).

EDIT: The issue appears to be fixed now, after reinstalling the cards one at a time, re-enabling crossfire, and overclocking again. Making sure that the power limit is properly set does also seem important, but I did have it set at +20% before as well and had the problem. Marking this as resolved though, because the problem is fixed.