Several hardware sites got their hands on Intel's new 45nm Xeon "Harpertown" processors. AnandTech published their ten-page long preview of the chipset and compares it against AMD's new Barcelona processors.
The new quad-core Harpertown Xeon processors are made on a 45nm process, feature a 1600MHz FSB, 12MB L2 cache, SSE4 instructions and other improvements. The reviewer lines up the 3GHz Xeon E5472 Harpertown processor against the 3GHz Xeon X5365 Clovertown and the 2GHz Opteron 2350 Barcelona processor from AMD. You can read the review at AnandTech.
In the performance area Intel achieves a 56% lead over the 2GHz Barcelona in some benchmarks. This is mostly because the Harpertown is clocked much higher, when the 2.5GHz Barcelona CPUs arrive the gap between both chips may become a lot smaller.
AMD has always been extremely strong in performance/watt, especially at the lower load levels and even more so at idle. Barcelona uses the least amount of watts at idle and manages to come close to the new Harpertown parts on AS3AP; however, Intel due to its 1GHz clock advantage takes the lead on every other benchmark, particularly at higher loads. Again, AMD needs to ramp clock speed in order to compete with Intel, and it looks like that will happen over the next few months. The question is, will it come soon enough to start winning back some market-share?