What is the fastest cpu compatible with compaq presario 2100 motherboard?

[cecilc]

 

[phil_livesey]

It's a discontinued socket type (PPGA478) You won't find any new ones, used ones will be very rare on websites like ebay. Pretty sure this is the quickest processor that supports your mobo: http://ark.intel.com/products/27599/Intel-Pentium-M-Processor-780-2M-Cache-2_26-GHz-533-MHz-FSB