[Slaggg]

Wait, wait wait. there's no need to go back. Dx9.0a was pretty unreliable when it comes to gaming applications. 9.1 is much better, from my experience.

Also, Sloi is right. Just think about it a bit. You have a OEM straight RAM Motherboard, and you're using a DDR vid card. The piplines are configured completely different. As all of that vid info travels through the channels to the vid card, it's running on straight RAM. When it hits your DDR vid card, a serious bottleneck occurs. It's no wonder your FPS drops like a stone.

Hopefully your Dell case is an ATX form-factor. If so, go out and buy a new DDR configured MoBo, take it and your comp to a good shop, and have em change your shit.