Phenom (/fɪˈnɒm/) is the 64-bit AMD desktop processor line based on the K10 microarchitecture,[1] in what AMD calls family 10h (10 hex, i.e. 16 in normal decimal numbers) processors, sometimes incorrectly called "K10h".

[2] Before Phenom's original release a flaw was discovered in the translation lookaside buffer (TLB) that could cause a system lock-up in rare circumstances; Phenom processors up to and including stepping "B2" and "BA" are affected by this bug.

BIOS and software workarounds disable the TLB, and typically incur a performance penalty of at least 10%.

"B3" stepping Phenom processors were released March 27, 2008 without the TLB bug and with "xx50" model numbers.

[4] An AMD subsidiary released a patch for the Linux kernel,[5] to overcome this bug by software emulation of accessed- and dirty-bits.