Overclocking
So how well does the Opteron 165 overclock? In order to find out, I slapped a Zalman CNPS9500 LED cooler on it and went to town, gradually cranking up the clock speed. The 165 was a model citizen, booting right into Windows each time with no hint of instability. With only 1.375V of power, a very modest overvolt, I was able to get this thing running at 2.7GHz—with air cooling. Check it out:

Note that in order to get the Opteron 165 running at that speed, I had to raise the HyperTransport link to 300MHz. The 165's default 9X multiplier nearly became the limiting factor in our overclocking efforts. Not every motherboard would handle that well, but our Asus A8N32-SLI worked like a champ. The only precaution I took was lowering the HyperTransport multiplier from 5X to 4X.

Unfortunately, one of our Opteron 165's two cores wasn't quite stable at 2.7GHz in Prime95, and raising the CPU voltage as high as 1.475V was no help. Ultimately, we had to settle for 2655MHz as our peak clock speed. For the tests below, I had the RAM underclocked slightly to 380MHz, just to be safe. That was about as close to a 400MHz memory clock as we could get with the HyperTransport link at 295MHz.

Believe it or not, our Opteron 180 was practically allergic to overclocking. There's typically less headroom in a high-frequency part, but in light of our Opteron 165's sheer willingness, I didn't expect to see the Opteron 180 throwing errors in Prime95 at 2.58GHz and 1.375V. More voltage, again, wasn't the answer. I eventually decided not to bother finding the limits on the 180 because it was so much less interesting than the 165. So, here's how the Opteron 165 performs at 2.65GHz...

Yep, it's really frickin' fast.