|"Memory multiplier 2.40"|
I didn't think the 2.40 multiplier was an option with an 800MHz FSB CPU? That's why I went with 2.66.
"BIOS error says the voltage is too high"
You don't need to touch the voltage settings, if you did, change the settings back to AUTO.
"I'll have to live with low res gaming"
Your poor gaming has nothing to do with the CPU, the problem is the video card. The 9400GT is NOT a gaming card.
"want some more ideas before I go buy a new desktop"
You don't need a new desktop, you need a gaming video card. Have a look at this article:
Best Graphics Cards For The Money: November 2010