Verdict: The Sempron 3800+ is not worth buying.

The Sempron was one of AMD's responses to the Intel Celeron, a series of cut-down CPUs for business PCs that will only ever run Word, Excel and Outlook, or for people who simply need to build a dirt-cheap PC.

At one time, there were more than seven different Semprons from which to choose, but the range has been cut down to just one model - the 3800+. This uses the same Socket AM2 packaging as other AMD CPUs, but has only one physical core, which is clocked at a miserly 2.2GHz.

Matters aren't greatly improved by the 128KB Level 1 cache or the tiny 256KB Level 2 cache. At least the 3800+ supports 64-bit instructions, SSE3, Enhanced Virus Protection and Cool n Quiet.

The 3800+ isn't the slowest CPU in this month's Labs test; that dubious honour goes to the Celeron 420, but it isn't far off. Its overall score of 389 in our Media Benchmarks means that it took nearly three times as long to complete the tests as a mid-range Core 2 Duo E6750 - so long that our tester Josh nearly fell asleep while waiting for the video encoding test to finish. A year ago, most games didn't take any advantage of multiple CPU cores, but modern games such as Supreme Commander and Crysis definitely like having more cores on which to run individual threads in parallel. Modern games also like having lots of cache to store frequently used data, so the 3800+, with its single core and tiny Level 2 cache, proved to be abysmally slow in every game we ran on it, with Supreme Commander crawling along at a jertktastic 3fps.

Just over £30 is an incredibly low price for any processor, but buying a Sempron really would be a false economy when, for just a few pounds more, you could buy a much faster dual-core Pentium E2100-series CPU.

• PSUs - 14th July 2008
• Multi-GPU graphics - 20th June 2008
• CPU water cooling - 17th June 2008
• Hard disks - 20th March 2008
• Audio hardware - 29th February 2008
• Graphics cards - 24th January 2008
• CPUs - 21st December 2007

• Cooler Master Cosmos S - Cases
• Lian Li PC-P60 Armorsuit - Cases
• Asus Rampage Formula - Motherboards
• Gigabyte GV-NX96T512H-B - Graphics cards
• Intel Core 2 Quad Q9300 - Processors
• Akasa Vortexx Neo - Other cooling hardware
• Zerotherm Hurricane HC92-Cu 8800 - Other cooling hardware