Putting a processor into a board that has a lower FSB will run it underclocked, if the BIOS recognises it and runs at all. It won't try to run at the rated FSB, as the board won't have components and BIOS that are capable. BIOS is what determines the speed, more so than the CPU itself.

debs3759 wrote:

Putting a processor into a board that has a lower FSB will run it underclocked, if the BIOS recognises it and runs at all. It won't try to run at the rated FSB, as the board won't have components and BIOS that are capable. BIOS is what determines the speed, more so than the CPU itself.

The 4E CPU frequency and multiplier is this:

The 4E is: 200MHz FSB * 10.5 = 2.1GHz
The 4D is: 166MHz FSB * 13 = 2.158GHz

Almost similar in terms of speed. I think I should purchase the 4D processor and keep the 4E in my ASUA A7V8X-LA motherboard.

That sounds sensible. I like to have earlier and later boards from each platform for testing and running the appropriate processors.

Not the same speed, the board will run the 4E as 10,5x 166fsb so indeed underclocked.

Not the same speed, the board will run the 4E as 10,5x 166fsb so indeed underclocked.

Your best option would be an Atlon xp-m (mobile) cpu. That's a 133fsb cpu but still with the 512kb cache Barton core. For example this one:
https://www.ebay.com/itm/AMD-AXMH2400FQQ4C-AM … P0AAOSwgiFaeTvZ

The 2400+ mobile has a 13,5 multiplier so running that at 166fsb gives a nice 2240mhz. Most of these Barton mobiles are capable of hitting up to 2,5ghz with a good board and cooler.

166MHz * 10.5 = 1.743Ghz