macbook white 2.0 ghz nvidia 9400m fps issues need help

I am not sure how long this has been going on, but my macbook behaves very oddly when playing games (will need to test more to see if it's all games or a select few),
but the fps in half life deathmatch is average 30+, after a maybe 10 minutes of playing it will drop to 20, and then unable to get above 16 it is like this in most games, and it's very annoying, average temp when playing games is 154.5 fahrenheit, or 68 degrees celsius, also if i close the game and wait a few minutes, i can play again, but only for a short time again, this seems to me like overheating, but i am not sure, i need some help with this and thanks in advance.

The nVidia 9400m is an integrated GPU which borrows memory from the system up to 256 mb. It's not a gaming GPU and is likely running out of steam (memory) as you play. If you stop and reboot, you can probably pick up and run 30 FPS again for a bit.

chscag said:

The nVidia 9400m is an integrated GPU which borrows memory from the system up to 256 mb. It's not a gaming GPU and is likely running out of steam (memory) as you play. If you stop and reboot, you can probably pick up and run 30 FPS again for a bit.

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are you sure? this does not seem to be happening to another macbook which has the same specs as mine.

You can look up the specs on your MacBook for yourself. Your graphics processor is an integrated chipset built into the motherboard (nVidia 9400M). As such it has no dedicated memory and must "borrow" memory from the system.

The following is taken from Mactracker for your MacBook:

GRAPHICS

Graphics Card NVIDIA GeForce 9400M

Graphics Memory 256 MB of DDR2 SDRAM shared with main memory (Minimum graphics memory usage is 256 MB)

ok that makes sense, but why does it only happen to some games?, it won't happen to a game with more intense graphics, it seems that the games it does happen to are mainly multiplayer.