Verdict: AMD's first quad-core CPUs, but incredibly slow at most tasks.

The Opteron 2300-series first appeared a couple of months ago, and were AMD's first quad-core CPUs. These CPUs were also the first to use the new K10 architecture, which has been improved over the earlier K8 architecture; it includes the ability to handle up to four floating-point instructions per clock, and features improved branch prediction and support for 128-bit SSE instructions and SSE4a.

The 2300-series CPUs also have a redesigned cache architecture. Each of the four cores is equipped with a 128KB Level 1 cache, a 512KB Level 2 cache and a large shared 2MB Level 3 cache that all four cores have to share. The 2300-series models are also made using a 65nm process, so they should be energy-efficient. Like all AMD64 CPUs, the Opteron 2300-series supports 64-bit instructions, as well as SSE3, Enhanced Virus Protection and Cool n Quiet.

Although AMD currently lists four models of Opteron 2300-series CPUs, we were only able to get hold of two models - the 2347 (1.9GHz) and 2346HE (1.8GHz). There's also a lower-speed model, the 2344HE, (1.7GHz) and a higher-speed model, the 2350, clocked at 2GHz. However, according to the distributors and retailers we contacted, the latter isn't available to buy.

AMD refused to send us any review samples of these CPUs, and we had to obtain them from retailers. The reason for this became clear when we benchmarked the 2347 and 2346HE. Both models were far slower than a pair of Opteron 2210s in our Media Benchmarks and game tests, despite being nearly twice as expensive. However, the 2300-series models were superior in Cinebench R10 and Folding@home, thanks to their additional cores (eight compared with four for a dual-CPU system). The 2347 and 2346HE also fared poorly against the Xeon 5300/5400-series CPUs - the Xeon E5335, which is similarly priced to the 2346HE, was 26-68 per cent faster depending on the workload. The 2346HE uses less power, 305W as opposed to 390W, but due to the performance difference, it's less power-efficient.

Although the Opteron 2300-series is faster than its 2200-series predecessors in some tasks, the CPUs' abysmal performance in desktop and workstation applications means that they're best avoided until AMD ramps up the clock speed by a gigahertz or more.

• 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
• Motherboards - 13th November 2007

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