Utilizing all 4 cores correctly? (with FRAPS)

I’m trying to record something in Far Cry 2 using FRAPS, and I need to keep the high framerate constant.
I’m not 100% sure in what way FRAPS uses the CPU (mostly for encoding, maybe?), but because of the problem that happens I think it’s supposed to be it.
I have a Q9550 Core 2 Quad (2.83Ghz), and from what I’ve understood, Far Cry 2 can utilize 2 cores, so basically it should leave FRAPS with 2 cores which is more than enough.
I’m doing some record where a physics calculation takes place at some point, and when it gets to this part the framerate drops lower than the set amount FRAPS uses (it doesn’t happen without FRAPS), and it gives an unsmooth playback.
I think that the real time physics calculations are taking place in the CPU, and FRAPS probably uses a core that is already used by the game’s physics to record and when it gets to that part it becomes too slow.
If it’s what I’m thinking it is, is there a way to assign it a specific core so it won’t be interrupted by the physics calculations?
Thanks in advance.
Answer #1
When you record something through fraps, it caps your FPS to 30 so it will look good on the video since videos are usually 30 fps. I am not completly sure if you can change this setting or not.
Answer #2
No, you didn’t understand.
There’s an option to change the capture framerate (up to 100FPS), but at the physics-point, and it only happens with fraps, it gets lower than the cap I’ve set for it, and it gives an unstable playback.
It’s supposed to be because of the CPU, so I want to know if there’s a way to make it use a free-core so the game and FRAPS won’t interrupt each other.