Help ! I have this old computer and I want to upgrade the processor for use by the kids. After researching processor I found that I could use a 700 mhz pentium III. I ordered one online, put it in and nothing ! Computer: Hp Pavilion 4455 Mother Board: D7394A or PS2KBMS Chip Set: 440zx/100 F Bus Speed: 66 mhz Socket: pga 370 Processor: Celeron 400mhz, 128 cache New Processor: Pentium III 700mhz, 128 cache Everything I read said this was the fastest possible upgrade. What am I doing wrong?

You might want to post back any links that led you to believe it would take a 700 mhz processor. I'm not saying it can't--I just didn't find any. I think this is the manual for the Asus motherboard that was adapted as an OEM version for your HP: http://dlsvr02.asus.com/pub/ASUS/mb... On that the cpu speed is set with jumpers. For a 700 mhz you'd have an fsb of 100 and a multiplier of 7. So assuming it has the jumpers you need to make sure they're set correctly. There's an architectural change in those cpus starting at around 600 mhz. I think basically they had different core and/or I/O voltages. If you google the S-spec number on both the old and new cpu you should be able to see if they're different. Obviously the motherboard would have to provide the correct voltages for the new cpu.

. . . Of course that assumes it was a good cpu in the first place and that you got it all put back together correctly. Sometimes a bios upgrade will include added cpu support. If one is available it should be on the driver support page for your model. You'd have to reinstall the old cpu to do the upgrade. (edit) There's a bios upgrade listed here: http://h10025.www1.hp.com/ewfrf/wc/...

You most likely have a motherboard that can only run PPGA Celerons based on the older Mendocino core. The fastest Mendocino Celeron ran at 533MHz. Pentium IIIs and P3-based Celerons would require an FC-PGA adaptor to work on a PPGA motherboard. The creme de la creme of Socket 939: Opty 185 @ 3.2GHz SLI'ed GTS-640s, both flashed to 625/1458/1950 4GB PC3200 Blu-Ray/HD-DVD, X-Fi A8N32-SLI Deluxe 3DMark06: 13896

Go here: http://www.tomshardware.com/2005/11... Click on the hammer icon in either bottom corner of the chart to expand it. If the graphic is still small, maximize the resulting window, right click on the graphic, and you may see a small grey square with an icon in the middle with arrows pointing outward to it's corners - click on it. You will note there are only two 700mhz cpus listed, both are Coppermine, and the Celeron runs at 66mhz. Your mboard may not be new enough to support Coppermine cpus, or it my only support the Celeron, or the mboard bios version may just not recognize the cpu type - these old mboards will not boot if it doesn't. Also the Mendicino cpus use 2.0v cpu core voltage, the Coppermines use 1.75. Lots of old 440 mboards can only use the Mendicino cpus, 533mhz max, because they can't set the core voltage to 1.75 or thereabouts. If that voltage is 2.0 and can't be changed, a Coppermine cpu will burn out in a short time if it works at all. Your 400mhz cpu is a Celeron.. D7394A is a Celeron (only) mboard according to some hits on the web.

As hinted by jackbomb & at the very best, the only option (for your 440ZX-66 based 370 motherboard) besides returning the PIII is an upgrade adapter like the -- long discontinued -- PL-NeoS370 from PowerLeap.

I believe this is a slot 1, If it is you will need a slocket adapter and a 370 processor. You can then go up to 1.2 ghz