The Phenom II X4 955 exists, and it's a pretty nice overclocker. At least, that's the impression you might get after reading a thread at the XtremeSystems Forums, in which a member has posted CPU-Z screenshots of the unannounced AMD processor running overclocked in the Windows 7 beta.
As you might remember, we last wrote about this purported Phenom II X4 955 two weeks ago. Back then, word was that the 3.2GHz quad-core CPU would hit stores in April, and that it would be a Socket AM3 part with a 125W thermal envelope and support for DDR3-1333 memory. That chip was also said to be a replacement for a 3.1GHz Phenom II X4 950, which AMD supposedly canceled because of better-than-expected yields.
Dumo from the XtremeSystems Forums shows the 955 engineering sample running at the stock 3.2GHz speed with a 1.25V voltage setting. At 1.45V with air cooling, the poster claims he was able to hit a cool 4GHz by pushing the HyperTransport speed from 200 to 250MHz—and he even has a screenshot to prove it. That screenshot shows Dumo also overclocked his memory to 1666MHz, which netted over 11GB/s of read bandwidth according to a Lavalys Everest benchmark.