Hi I have athlon xp 2000+, MSI kt3 ultra2 MB and DDR333 ram but when I set fsb to more than 139 windows xp crashes all the time. Increasing Vcore doesn't help. CPU at full load is 50C, MB 32C. Is it possible to do more than just tiny 4-5% increase? I can overclock my celeron 1200 easily to 1400.

Then that probably is as far as you will be able to go with that method. You could unlock the cpu but not recommended. If your system is stable at 139 then i would leave it.

Ugh I too am having problems with an MSI kt3 and XP 2000+ Mine wont go faster than 1.250G withough losing stability. Ugh, been pulling my hair out over this.

Dont gripe, im on a p.o.s. Compaq Presario 700mhz Celeron @ 900mhz (my dad bought it w/o consulting me :(. I wont be getting another computer for another 6-8 months and the damn thing has an all-in-one chipset which means i have no agp slot to put a nice video card in (like that gf4 kid... poor bum) 1.2ghz is not bad, especially if its an athlon which translates to 2.0+ghz!

As your posting in here you most likely have a clue. I will however pass on what I have found. I would remove all your hardware down your bus and try pushing it back up over 139. You may find that the stability may be there after that, then you can install each of your pci components one at a time and see if one of them is dragging you down, I beleive that at 139 you running the PCI bus around 35 mhz and perhaps something you have there can't handle more than the 66ish that's standard. Anyway, I have pushed MSI but not that board to 147 stable, but perhaps that's all the PLL on your particular board can take.

Ok. Well, I dunno about this BUT! I just configured and put together my new system. KT333 (ECS K7VTA3 v3.1) XP2000. In the bios there is an option for bus speed (100/133) but also an option for RAM (100/133/166). My ram is set to 166 bus 133 CPU bus (2x 16 =332mhz and 2 x 133 is 266mhz for cpu). You are messing with the wrong setting, and overclocking your cpu, which is why it is crashing.