I have had to install a new Socket A motherboard & AMD Celeron chip. The CPU FSB is rated 266 but in the Bios it comes up as 133 if set to Auto. If I set it manually to 266 then the computer won't start up. Also the memory comes up as 333Mhz when it is in fact 400Mhz. Leaving everything on Auto then it all works but surely I'm loosing a lot of speed here. Many Thanks

There is most likely a jumper on your board but because you have not listed your system components then were just shooting in the dark. Also,AMD don't do 'celerons'. Tt Lanfire MSI K8N Diamond X2 4600+@234x12=2.8ghz 1:1 1GB PC3200/4400 OCZ Powerstream 520w 7900GTO WDCaviar 160gb sata x2

I was about to say, damn AMD buying out everyone these days. :) AMD Athlon 64 X2 4600+ OC 2.7ghz 2GB Dual Channel DDR 3200 Nvidia 7900GT SATA II 2x 300gig 7200rpm 16mb cache RAID-0+1 Gigabyte Nforce 4 SLI

Whoops. Far too much reading and my brain is fried. It's of course an AMD Duron 1800 FSB 266. I have already set the jumpers on the motherboard to 266. Any other ideas. Thanks

Should have spotted it in the 1st place,doh. 133 is 266 it's correct. DDR=Double Data Rate therefore 133x2=266 When you try to set it at 266 it's actually trying to be 532 and definately won't start. Try and run your ram async aswell at 266 not 333 or 400. Tt Lanfire MSI K8N Diamond X2 4600+@225x12=2.7ghz 1:1 1GB PC3200/4400 OCZ Powerstream 520w 7900GTO WDCaviar 160gb sata x2

AMD "double-pumps" the FSB. Although the advertised speed is 266MHz, the actual setting is 133MHz. Your 1800MHz Duron is clocked at 13.5 x 133MHz. DDR-SDRAM is also double-pumped. DDR266 runs at 133MHz, DDR333 runs at 166MHz, DDR400 runs at 200MHz, etc. And although you apparently have PC3200 (DDR400) RAM, it should be clocked down to match the speed of the FSB. In other words, manually adjust the RAM setting to DDR266 (133MHz) so that it runs at a 1:1 ratio with your 266MHz (133MHz) FSB CPU. There's no point running the RAM faster than the CPU...1:1 ratio will give the best performance.

Many Thanks to everyone. Everything is so much clearer now.