Which new CPU for MSI P965 MoBo

Your are correct, your board does not support the FSB for the e8400.
One of these 3 would be about the best you could do.
http://www.newegg.com/Product/ProductList.aspx?Submit=E...
And yeah, any of these processors will net you a big performance gain.
You will also need the latest BIOS, revision 1.8 to support Wolfdale processors. Make sure you have this, or updated to it before you install the new CPU.
You don't need to do a thing with your memory, it will be prefectly fine.

• Supports FSB 1333/1066/800/533 MHz

The CPU Chart clearly shows support for 1333MHz FSB (e.g. 333.33MHz quad pumped). However, BIOS V1.8 was released 12/01/2007. I don't know how MSI can claim P965 Platinum supports most of those Wolfdale and Yorkfield models with a BIOS that contains no CPU microcode revisions later than 09/12/2007. Almost all (if not all) motherboard BIOS that added support for 45nm in 2007 had to be reworked with newer microcodes because most were based on engineering samples that proved buggy as hell with production silicon.

Numerous P965 Platinum users have reported very buggy behavior when trying to run 45nm processors with BIOS V1.8, particularly the later steppings of those processors. The support status of 45nm processors on this board with BIOS V1.8 really should be designated UNSUPPORTED BETA. There will be no further BIOS releases.

How does the motherboard support 133mhz FSB, when the P965 chipset only supports up to 1066? (look farther down the spec sheet) I suppose the board could have an overclocked setting that it runs to get 1333, that would be a good arguement for the instability of the board running these processors, I would suggest.

Same way that motherboards using Intel chipsets have been supporting DDR2-1066 for the past two years, in spite of the fact that Intel has never qualified any of its chipsets beyond DDR2-800 (including X38/X48).

65nm 1333MHz FSB processors run just fine on P965 Platinum. Only 45nm processors are flakey.

Forget about running the E8400 on the MSI P965 platinum .
Got the same mobo and buyed the E8400 few days ago . Flashed the bios to the latest ( with which MSI claims the E8400 should work ) ...

But it doesnt work.