My Motherboard can support an upgrade to Athlon XP2600. I know how to physically install it but what happens then. Does the BIOS (AMI) recognise it automatically or what. Many Thanks

If my guess is correct your MBoard runs FSB266 and can run durons and Athlon thoroughbreds. The fastest one I see listed is 2700+. If your Board has the latests BIOS you should be good to go. Otherwise you may need to Flash the BIOS. Check your BIOS version, it shows the version during the POST screens. Then check the manufacturer's website to see what processors are supported by that BIOS version. Most likely it will work without a problem, but better to prepare now. If you can't run it, you would need to swap the old processor back in to Flash.

Thanks for that. Yes you're right, FSB is 266. According to GigaByte web site the fastest is 2600 with BIOS Ver 4, (I have Ver.5) but it seems in the UK the 2600 is now only available with FSB of 333. So I wil have to go down to 2400. Unless I can run a 333 on a 266 Mobo ?

if you tried to run a 333mhz FSB processor it would clock it at 266 FSB and give you a much smaller clock speed, best off getting a 2400 or investing in a new board aswell. Q-TEC 550 Watt PSU MSI VIA KT4AV-L 2800+ Barton 512 DDR333 GeForce4 Ti 4200 128Mb Aero 7 Lite 80Gb Samsung ATA133 HDD 120Gb WD ATA100 HDD LiteOn LDW-851S LiteOn LTR-52246S

The 333FSB chips are Bartons. I don't think they are compatible, but I am not sure. Newegg.com has a 2700 thoroughbred listed, so the speed ramp must be at least to 2700. The sweet spot in the price may be a little lower than that though. You would need to decide that for yourself. Keep in mind that the CPU speed is only one part of the system and that frequency alone is not an accurate guage of performance. Just look at P4 versus AMD. The 333FSB and 400FSB chips of equivilent frequency will out perform that 2700 266FSB. The bandwidth on the memory side also holds performance back on 266FSB. All I am saying is if you increase the chip frequency by 50%, don't expect a 50% performance gain. The percentages I just used are for example only, I didn't bother to check the actual frequency of the 2700. You get the idea.

2600+ Barton (333FSB) runs at 11.5 x 166mhz 2600+ Tbred (266FSB) runs at 16 x 133mhz If your board only supports 266FSB & you drop in the 2600+ Barton, it would run at 11.5 x 133 (1533mhz), which is the equivilent on an 1800+ Tbred. If you can't find the 2600+/266FSB version, go for the 2400+ as was suggested Asus A7N8X-X 2500+ Sempron @ 2100mhz 10.5 x 200mhz @ 1.80v 512mb PC3200 Ti4200/8X 128mb WDC 60GB