Originally Posted by Mookster
It's interesting that the frame latency is so low from the first card, and then so high from the second. From 10ms to 25ms consistently.
I'd like to know more about the test method. I might be wrong in my understanding, but if there is infact 15ms difference between the first and second card, that means either frames from one appear before frames on the other card (this would of coarse be very noticable) or, the crossfire config is only able to create 8 frames per second, which would also be very noticable.
I've never experienced anything so extreme on my 6950 setup, so these results seem questionable to me.
It's easy, just get fraps and do a frame time benchmark. But then the hard part is making something out of the infomation overload it gives you.
Not really, single GPUs don't suffer from micro stutter but dual GPUs do because it's hard for them to be in perfect sync. It's important enough that the GTX 690 comes with an imbedded controller to handle differences in frame times and smooth them out, hence the great performance it gives you over a traditional dual-GPU set-up and was the main reason I bought one.
AMD just need to arknowledge it's existence and improve it either at a driver level or a hardware level, whatever causes it and be done with it because they are the worst culprits. Ask anyone with an HD 6990 and they should suffer from it a lot, if they say they don't they don't know what they're talking about. Realistically it shouldn't be bad enough to bother you but in a lot of cases it is.
My understanding of micro-stutter is it represents the time between each frame is rendered. A constant 16.7ms interval between frames will equal 60 frames per second. What the HD 7970 cross-fire is doing is the first GPU will render the first frame in around 10ms and the second will render it in around 25ms meaning every second frame your pausing to recieve it on screen, recieving constant speed ups and slow downs and causes a jittery screen and flickering textures. With them not being sent in a consistent timing the screen can not look smooth, it's simply impossible. The extent to how severe it is, is however up to the set-up.
Apply that to something slower like a gun firing, every shot pausing a second then every second shot pause 2, then speed it up and it's going to look retarded. Do the same thing with shots being fired at the same 1 second interval and speed it up and it'll just look like a regular automatic weapon firing.