DDR-533 for Athlon 64s Posted on 11/07/2005 at 15:14 by Marc
The latest E version of the Athlon 64, that adds SSE3 support, also brings something little talked about that AnandTech came up with ; support of memories without overclocking that go faster than the DDR-400. Mentioned in FX-57 documents under the heading “DDR-533 support”, this capability deserves some explaination.
In Athlon 64s, memory frequency is calculated acording to the folowing formula:
Ceil is a function that makes the whole number superior to the ensuing division. In the new Athlon 64s, AMD simply added new memory dividers:13/12, 7/6, 5/4 and 4/3, additionally to the 1/1 divider required for the DDR400 (200 MHz) with HyperTransport bus to this frequency. Results with the formula are the following dividers according to the processor frequencies:
This gives us the following memory frequencies :
The bios in the DFI LANParty UT nForce4 Ultra-D and Fatal1ty AN8-SLI function with these new dividers and the gains are up to 9% in memory bandwidth tests. Gains in applications vary between 0 and 5%.