Can't increase FSB with AMD 2.6

[clemolo]

Hello, I have just upgraded from an AMD 1.1gig to and AMD 2.6+ processor. Problem is it only runs at 1.25gig, which is not much better than my prvious chip. I cannot increase the FSB to more than 104. Anything above that and the system locks up or the blue screen of death appears. with a message that windows is dumping the NVmemory.
My main board is MSI KT4V which should be able to run up to 280FSB. Memory is 512meg PC 2700 set at 333 speed (using auto mode)

Many thanks for any help
Ray Clements

[Surge1243]

Welcome to PCMech!

Are you talking about an Athlon XP 2600+? If so, is it the 333 MHz fsb version or the 266 MHz fsb version. The 2600+ does not run at 1.25 GHz...it sounds like your FSB settings are incorrect in the bios. If the cpu is the 333 version, make sure your BIOS settings are set to an FSB of 166 and if it's the 266 version, set it to an FSB of 133. If you cannot find the option in the BIOS, check the board itself for any jumpers that may need to be moved to change FSB.

[clemolo]

Thanks for your help but the problem is that I can't set the FSB to any more than 104mhz. If I try to the computer becomes unstable, so there is no way that I can get to 160. There are no jumpers on the board all the setting is done in the bios.

[TwoRails]

Maybe you are thinking of 100% ratio of the fsb?? If the memory is running correctly at 333, then the fsb should be set OK. Did you set the mobo to Auto for the CPU or did you set manually the multipler?

[clemolo]

Thanks TwoRails. The multiplier is set to 12.5 I tried to change it in the bios but I think it is hard wired into the CPU.
If I try any setting other than "auto" It reacts strangely. for instance I set it to 20 but when I rebooted it was only reading 5. The FSB is definately set to 104 and the system becomes unstable if I increase it any more. I am wondering if the CPU is faulty. I did send an email to AMD but waiting for a reply.

[crjdriver]

There are dividers for your fsb, they allow the pci to run @33 as it is designed. Each divider kicks in at the appropriate fsb setting. When you set 104fsb you are actually over clocking your pci / agp bus. When you set the fsb to 133 you should see the pci / agp return to 33 / 66. This will happen again @166 [and 200] if your board supports that speed. You need to make sure which cpu you have, they are available in either 266 bus or 333 bus. Most common is the 333; for that you will set 166 for your fsb setting in the bios.

[clemolo]

Thanks a million CRJ your suggestion helped me out and problem seems to be solved. My CPU is the 333 model and setting to 166 brought it up to speed. Thanks once again