Overclocking
High-end CPUs like these generally don't have lots of headroom left for overclocking, so I was pleasantly surprised by what I got from these two processors. The FX-55 was the real star, because its unlocked multiplier allows for very low effort overclocking—just set the multiplier a little higher and go. In a few tries, I was able to determine that the FX-55 would run just fine at 2.8GHz, but no more. The system wouldn't POST with the CPU set for 2.9GHz.

The 4000+ suffered from a weakness of our Asus A8V Deluxe mobo. This is an earlier revision of the board that lacks an AGP/PCI lock, so overclocking the system bus makes the whole system run out of spec. As a result, we were limited to about a 220MHz bus, at which point the 4000+ seemed very happy at 2.64GHz. I was able to get it to POST and boot into Windows on a 225MHz bus at 2.7GHz, but the system crashed and corrupted my Windows installation. I suspect this 4000+ would handle at least 2.7GHz just fine in a mobo with a proper AGP/PCI lock.

The test results below aren't as stellar as they could be for the overclocked 4000+ because I was playing it conservative with the RAM, which was clocked at 366MHz with 2-2-2-5 timings. A little extra tuning might have yielded better performance with 440MHz RAM.