4th December 2007

BIOS fix for Phenom 9500, 9600 erratum lowers performance

posted by Eric C. in Hardware, Processors |

An erratum, which is a bug in the logic of a chip, in the translation lookaside buffer (TLB) logic in the L3 portion of AMD’s quad-core CPUs affects all current quad-core models, Phenom 9500, 9600 and “Barcelona” Opterons, can be fixed with a BIOS update but the workaround can lower performance by 10%. A TechReport source said it could be more like 10-20%. AMD has even gone as far as to stop shipping quad-core Opterons to OEM server builders and to channel distributors over the erratum. According to AMD the erratum only appears under certain circumstances with a heavy workload and creates a system hang.

In contrast to prior AMD statments, AMD denied that the TLB erratum was the reason the clock speed was kept at 2.4GHz for the initial Phenom models. AMD has passed along the BIOS fix to motherboard manufacturers but their doesn’t appear to be any BIOS’ with the fix released yet, with no ETA announced. They also said that PC OEM partners were informed of the erratum before launch and should have fixes available.

The Phenom 9700 running at 2.4GHz and the 9900 running at 2.6GHz will be a new revision, B3. AMD does not plan to fix the erratum in the Phenom 9500 and 9600. Instead they will release new models based on the fixed B3 revision, the 9550 and 9650.

If this is indeed the TLB erratum that AMD already knew about and initially blamed the low clock speed of the Phenoms on, why wasn’t this fixed to begin with? Perhaps I need to take off my tinfoil hat, but I can’t help but wonder if they delayed the fix to save some face and make the initial Phenom benchmarks less embarrassing, especially with the statemnt that PC OEM partners were informed before launch.

There is currently one response to “BIOS fix for Phenom 9500, 9600 erratum lowers performance”

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  1. 1 On December 5th, 2007, Eric Chevallier said:

    new info on a Linux kernel patch for the TLB problem http://techreport.com/discussions.x/13742

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