Advanced Micro Devices Inc (AMD)

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Opteron Overclocking Results

http://www.amdzone.com/articleview.cfm?articleid=1299

Using a 1.6GHz Opteron:

Beginning at Cas 2 with default voltages we gradually raised the CPU overclock value above the 200MHz mark jumping in 2-3MHz intervals. We tested memory benchmarks and 3D benchmarks to measure stability. When we reached 210MHz for a 1680MHz speed we began having trouble with 3DMark2001SE and Gunmetal benchmarks. All other 3D benchmarks like Quake Arena, Code Creatures, and UT2003 ran flawlessly. We upped the AGP voltage 0.1V at a time until we reached the maximum 1.7V, but this did not allow the benchmarks in question to finish. It could be that the AGP bus was too far out of spec at this point to complete this benchmark. All other non 3D benchmarks ran without crashing.

When we moved to 212MHz none of the 3D benchmarks would finish, but all over benchmarks ran normally. We edged up gradually until we hit 220MHz for a total CPU speed of 1760MHz without additional problems. At 222MHz we had to raise the DDR voltage to the maximum of 2.7V. This allowed us to benchmark with non 3D applications except SuperPi which is one of the more sensitive benchmarks in regards to overclocking.

Next up was 225MHz. The system would post, but would crash when loading Windows. We upped the Cas latency to 2.5 and finally to 3 and we were able to get into Windows at 244 speeds. The 225MHz setting gave us a total of 1800MHz. This is documented in the CPU-Z screenshot we took. CPU-Z recently received an update that provides full Opteron and Athlon 64 support.

So it looks like 1.68GHz is the limit for full AGP compatibility (5%), while 1.76GHz is the highest possible in Windows without OC tricks (10%). With a boost to DDR voltage and a lower CAS latency, 1.8GHz was the highest achievable overclock (12.5%). It seems pretty clear, then, that Opteron has very limited headroom. A lot of work will have to be done before Athlon 64 can launch with full AGP compatibility at >2.0GHz.