ATI Radeon HD 4000 Series discussion

[trinibwoy]

It is clear with different frame times.

The only thing nobody explains - why would the frames be so different all the time in the middle of game? I would understand they differ at the moments of begining of changes of picture like new big object appears on the screen. But! next frame would still have it! If you say that object changed position/size and next frame would require more processing? -Ok. But it supposes to remain on next frame(s)! So time difference should spread over all consequent frames pretty evenly...

So it should not stutter?!

Depends on the game. In something like a racing game where the game world is going by rapidly and the view is changing at a high speed the stuttering can be very noticeable. In an RTS or RPG and most FPS's it won't be that noticeable. And the issue isnt about how long it takes to render the frame on each GPU. It's about the timing of when frames are delivered to each GPU and how long each rendered frame stays on screen.

The problem with it isn't only that you notice it. The other big problem is that the big fps numbers are false. In some scenarios (highly GPU limited) you're getting essentially the same frame rendered twice in a row followed by a long delay then two similiar frames rendered in short time etc. That's why some people find single GPU play "smoother" even though the FPS numbers are lower.

AFR doesn't work well in extremely GPU (frames thrown away, stuttering) or CPU limited situations (no scaling). The sweet spot is somewhere in the middle (my second diagram above).