Hey, I've made a thread about this before and I was told it's normal, but this is unbearable and it's running terribly for how much I paid for it and compared to my old Nvidia GeForce GTX 260.
GPU: HIS Radeon HD 6950 Iceq x Turbo 2GB
RAM: 8 GB
CPU: AMD Phenom II x4 3.0 GHz
OS: Windows 7 64bit
PSU: 500w (I thought this was bottlenecking my setup but I've seen others getting the same problems with a better PSU)
When I play games like League of Legends, I get a average of 60 FPS and then it'll spike down to like 40 or even 30 during intense battles or smoke. I've tried lowering and raising the graphic settings with no difference. I can't even run Call of Duty: Modern Warfare 3 anymore because it's so choppy and when I look to the left and right it sometimes will skip a frame and it's really noticeable.
I've tried changing my driver version from 12.3 to 12.2 and even down to 11.9. I'm running out of possibilities and I even made a support ticket on HIS' website, but they're no help. It takes them several days to respond.
1st thing I'd do is check your card temps right away! while a game is running, alt-tab back to the CCC and check the GPU temp and fan speeds.
Could be your card is overheating and its auto-throttling the GPU speed down. If you are seeing 70C to 80C, you are at the limit.
If it is starting to cook, make sure your fan is spinning at an appropriate speed (if at all). CCC lets you manually set it the RPM speed. This setting may not work with all cards, so if HIS has its own fan monitor and control, check that too.
You may also want to tighten up or even repaste & reseat the Ice-q heatsink, for good measure, if it is overheating as well.
Hope that helps.
I would say its not normal I can easily run MW3 with one of my 6950. In fact most of the time my second card is disabled because CF is inefficient for most games. I agree with old_newbie, do a stress test on your cards with but with Furmark. Are the fans on the cards working properly? I Found that the fans on my 6950's don't respond properly to temp increases. So I use Trixx to control fan speeds. This will help, but I dont think that would account for such drastic FPS drops. Also, 500w is not much power. So a new PSU is probably worth looking into. Also Hwmonitor is a good way to watch temps. I dont particularly care for CCC.