We have been testing the overclocking capabilities of the Phenom II X4 940 (seriously, who names these products?) for an AMD roundup and have hit the proverbial brick wall. It has not been for the lack of trying or even using a stellar motherboard to test these processors. The motherboard choices have ranged from some wicked little 790GX overclockers from ASRock, Gigabyte, and DFI to the flagship 790FX products from ASUS, MSI, and Foxconn. We even tried a few NVIDIA 780a based motherboards along with a slew of newly arrived AM3 compatible boards. We changed cooling, processors, video cards, disk drives, memory, and tried every available voltage setting. It did not matter. We could not break the 4GHz barrier and still complete our benchmark test suite.<br>
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The only commonality between our 30 different setups is the operating system. We recently standardized on Vista Ultimate 64 SP1 for testing. Granted, we had this same problem when our 940 engineering samples first arrived and we asked AMD about it. However, AMD never did get to the bottom of it before the launch date. We thought our results might change with retail processors. Alas, they did not. We have four retail CPUs, three with 0850 lot codes and one from the 0849 batch that all behave the same way under Vista 64.<br>
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At least under Vista 64 as Vista 32 was much different. The settings mentioned earlier allowed us to reach a stable 4.275GHz (19x225) with the same components. However, we are not utilizing Vista 32 in testing anymore, especially considering our standard benchmarks are completed with 4GB and 8GB configurations on the DDR2 platforms. As such, it appears at this time that any overclocking comparisons will be limited to under 4GHz on the AM2+ and AM3 platforms. We have addressed this problem with AMD again and hopefully an answer is forthcoming. In the meantime, we figured out a way to get a screenshot above 4GHz before we received the standard BSOD routine. At least it is a consolation prize at this point.

http://www.anandtech.com/weblog/showpost.aspx?i=550

Isn't it a known that going from Win98>2000>XP>Vista>Vista64b overclocks come less stable? as more checks are performed by the OS and uses the hardware differently (more?)

I still remember AXP overclocks which were 100% stable under Windows 98, would BSOD under 2000/XP

Yes, that was a really pointless article. Anandtech themselves ran an article stating Vista 64 was far more demanding on hardware than Vista 32, and decreased the top overclock.

I have no idea why Gary would forget that so quickly. I think he is expecting far to much from AMD's chips.

WOW yea thats a good point. What were they thinking with this?