Bad Performance Gaming

TwistedFury

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I just replaced my GeForce GT 240 with a GTX 460, but when I started playing multiplayer on BF3, the performance is worse! I lag really bad on low, and I know that even with my Athlon II x2, it should atleast run well on low with that card, but I get like 20-30 fps, and it sometimes even randomly spikes down to 3-5. Can anyone help me with this?
 

TwistedFury

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I have a 500 watt PSU, I did the drivers, and it turns out, other games run well! I have MW3 on high and it runs around 80-100 fps so I can probably max that out, BF2 maxed out 100+ fps, it's just BF3 that is the problem.