Q: Xserve 2009 works with core i7 (1366 socket) 130W power?

I haven't tried it, but I find it extremely unlikely.

True, the socket type might be the same, but you have no user-level control over the clock multiplier, and that's what determines the processor speed.

The 3.47GHz processor requires a clock multipler of 26x, however, the XServe doesn't provide any controls over the multipler that you set. Therefore I'd expect the chip to run at the same frequency as the existing processor (assuming it runs at all). You might get better performance through the extra cores and later technologies, but I wouldn't expect you to get the higher frequency.

I might be wrong, though, and I"m not inclined to drop $2K just to try, at least not without a good return policy.

I know this is an old post but it would seem that the W5590 will work in the 2009 Xserves. I have not personally tried it yet. There are a handful of companies that sold this upgrade for a while. It may say "Unknown" for the chip type in the about screen though. With the 2006 Xserves you could upgrade the 5060 Xeon chip to a Xeon X5365 CPU Processor SLAED | 3GHz I did this on my 2006 and it was a MASSIVE difference. It also has the G0 stepping so power consumption is the same for the most part, however it doesn't see it as a Xeon chip in the about screen it just says unknown 3hz quad core. Works great though

It works great. The heat depends on the load, my server is not so heavily loaded so there is no problem at all. The processor lid is a bit tricky. It makes the chip about 2 mm thicker. First I was afraid I might crash the processor by over tightening the screws, but it did not work at all, lots of red lights by the memory modules due to bad contact. So I gradually tightened the screws until the server stared up nicely. A boost from 2.26 to 3.32 is a big difference. I have tried delidding once, it did not work out well, half of the die followed the lid, the rest stayed on the board.