asus p2b upgrade p2 300mhz to P3 850mhz

first off what revision of the board do you have,and do you have the latest bios installed.the earlier revisions do not support coppermine voltages. i believe the p2b only supports multiplyers up to 8x and 8.5x is not recognized,but it "may" run since the multiplyer is cpu locked and can not be set on the board. set the fsb to 100.the voltage is automatically set by the processor .if you have stability problems it could be you need a microcode update for that processor.

You'll need to verify the regulator chip is capable of CUMine voltage, 1.7vdc. Find the regulator chip (close to the slot 1). Look at the manufacture numbering on its surface. If the numbering ends in BCB, the motherboard regulator can cope.

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Try these two sites. They will tell you alot.
http://www.asus.com.tw/Products/Techref/Cpu/p3cpu.html
This site will tell you how far you can go, without overclocking.

Next will be the manual which lists all the jumper settings.
http://www.asus.com.tw/products/motherboard/manual.html
It is in .pdf format but it is a small price to pay.

Hope this helps!

Have the ASUS MB P2B-b and am having same dilemma. Manual only list CPU's up to 450 pII and Celery 366, Extra leaflet upgraded the manual to PIII 600 using 6 muliplier times 100mz,and Celery 500 using 7.5 miltiplier times 66mz. Local computer shop web site lists 750 PIII at 100 mz for sale. Don't see why 750 wouldn't workd unless they changed voltage. Checked Asus site, and doesn't list upgraded leaflet. Don't think that an 850 will work.

I had a similar problem with my old Abit BH6 Rev. 1.01. Abit oficialy said, that no Coppermine over 600 Mhz. works on it. I made a Bios-Upgrade for Coppermine Microcodes, set the voltage to 1.65V, used a noname FC-Pga Adapter and a Coppermine850@952 is running fine and fast.

If your board don't support 1.65V you can try one of this new FC-PGA Adaptor-Cards showed on Cebit with voltage regulator. I don't remember the manufacturer, but try to ask your local dealer.

Also be aware not buying a Coppermine with 133Mhz FSB, because at 100 Mhz FSB it runs slower due to the locked multiplayer. P3-850 exists only with 100Mhz FSB.