Would my HP Vectra VL400 be compatible with a 1.xGHz P3 (1.2/1.3/1.4)? If not, is a 1.xGHz (1.2/1.3/1.4) Celeron compatible? is a 1.3GHz Celeron better then a P3 1.0GHz for overall performance?

Never heard of it b4, check this out it might help...http://www.itreviews.co.uk/h207b-hp-vectra-vl400-review.htm

After wading through hp support for about an hour, I found out you have a PIII 1.0Ghz socket 370 Coppermine processor. The fastest Coppermine is 1133Mhz (1.13Ghz). Only problem with the 1.13Ghz PIII Coppermine is that it was stillborn and Intel pulled it off the market. So, you've got about the best Coppermine core PIII out there. Now the Tulatin core PIII processors worked well and were clocked up to 1.4Ghz...that's the good news. The bad news is that most boards manufactured for the Coppermine core won't work with the Tulatin core PIII and I think yours falls into this category. The two processor cores work at different voltages 1.75v vs 1.50v and hp quit using this board with the VL400. BIOS version IP0106 (you obviously have that version or a later version) also tells me a bios rewrite was necessary to recognize the D0 stepping of the 1.0Ghz and it's unlikely the motherboard would detect something like the 10.5 multiplier of the 1.4Ghz. BTW, the board uses an Intel Solano i815 chipset. So after all this, my answer is that I don't know; but suspect you've got about the fastest processor your machine can handle. The celeron alternative isn't worth any effort either as the same parameters apply. For the sake of argument, if you were able to get the 1.4 processor to work, I don't believe you'd notice any real performance improvement. Skip

For the sake of argument, if you were able to get the 1.4 processor to work, I don't believe you'd notice any real performance improvement. I completely agree here. To see a system get faster, increase the ram and get a faster hard disk - a barracuda, cheetah or the likes of those. and skip, needless to say, his board wont o/c right? Good Luck and Happy Computing, Kailas Shastry, Sempron 2400 underclocked to 1GHz...just for the heck of it! MSI KT266VM DDR 256MB

"needless to say, his board wont o/c right?" Not to my knowledge. CPU parameters are autodetected and I don't think you can do anything with the 133Mhz fsb and it likely will not detect a higher multiplier. As I understand it, the i815 chipset was originally aimed at oem manufacturers only and never intended for consumer use. Something may have changed later on but I'm just not aware of it. Still, that machine is no slouch...might need some video card help but otherwise it looks pretty good to me as is. Skip

"is a 1.3GHz Celeron better then a P3 1.0GHz for overall performance?" The Pentium3 1ghz will outperform a Celeron 1.3ghz processor BUtta My Fries Abit NF7-s Athlon XP-M 2600+ @2.5ghz 200x12.5 1024mb PC3200 Geforce 6800

To make it short all the others are right. I updates my Asus P2B a couple of years ago and got to the same results. The only difference was that my board was no OEM board but my revision didn't really support 133MHz. There was an undocumented jumper setting for 133MHz FSB but it didn't work right with the ISA slots. The fastest 100MHz FCPGA CPU is a Pentium3 1,1GHz Coppermine Core. I was trying to get one for my upgrade from a Pentium2 350MHz but because of the costs I settled down with a Celeron 733MHz which I overclocked to 1232MHz. Still even the 1GHz P3 would be faster but that Celeron cost about a quarter of the 1,1GHz P3 and was enough until now to work a secondary system for older lan games and multimedia!