Last month, Nighthawk hit the wall when attempting an overclock to 3.4 GHz with the stock HSF. High temperature was the suspected reason for this failure. I was perfectly content to back Nighthawk down to 3.2 GHz and it has been running at that speed until yesterday.
With its new Zalman HSF and lower operating temperatures, it was inevitable that I would make another attempt at overclocking Nighthawk to 3.4 GHz.
The first step was to go into BIOS and change the DRAM:FSB Ratio back to 1:1 (DRAM:FSB) ratio by setting DRAM Frequency to DDR2-640 before changing the CPU Frequency from 320 MHz to 340 MHz. The DRAM Frequency followed to DDR2-680.
I ran Memtest86 v1.65 for a couple of passes (approximately 45 minutes per pass for 4 GB of RAM) just to confirm memory stability.
I restarted Nighthawk and allowed it to come to an idle state before taking temperature readings.
At 3.4 GHz, the motherboard stayed at the same temperature (28C/82F) and the CPU temperature increased by 1C (39C/102F) compared to the temperature readings at 3.2 GHz with the Zalman HSF.
The next step was to fire up Johnny Lee's SP2004 ORTHOS. I was dismayed to see Nighthawk hit the same wall when it had the stock HSF.
Obviously, high temperature was not the only factor in this failure to reach a 3.4 GHz overclock!
I noticed a disparity between the CPU VCore Voltage setting in BIOS (1.4000V) and the reading in Everest Ultimate which was lower. Furthermore, I noticed that starting Johnny Lee's SP2004 ORTHOS dropped the CPU Core voltage even lower!
I increased the CPU VCore Voltage in BIOS from 1.4000V to 1.4500V, restarted Nighthawk, and started Johnny Lee's SP2004 ORTHOS again.
It has been running without any problem for over 20 hours as I write this post with the CPU temperature not exceeding 51C/124F.
Nighthawk has achieved a stable 3.4 GHz overclock with temperatures I can live with!