L3 cache unlockable on Athlon II X4 620?

It's been known for some time that the Phenom II X3 processors can have their fourth core enabled, effectively turning the chips into quadcores. An eXtremeSystems forum user has found a way to enable the L3 cache memory on an Athlon II X4 620 processor by using the ACC functionality in the BIOS, resulting in a significant performance increase in several benchmarks.

The Athlon II X4 620 comes without L3 cache and has a clock frequency of 2.6 GHz. The quadcore chip features 512 KB of L2 cache memory for each core and sports a 95 Watt TDP. The processor is also compatible with DDR3 memory.

Normally, the Athlon II X4 620 should be built on a "Propus" core, which physically misses the L3 cache and is therefore cheaper to produce. Because the Athlon II X4 620 allowed its L3 cache to be enabled however, it's possible that AMD is currently using partially defect "Deneb" Phenom II X4's, which do have L3 cache. After the introduction of "Propus" it will no longer be possible to enable the L3 cache memory.

Two screenshots showing an Athlon II X4 processor, with and without the L3 cache enabled.

Tags: ddr3 deneb phenom athlon

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