FIRST LOOK - nForce4: Gigabyte K8NXP-9

Overclocking and Memory Stress Testing

With the limited ranges of CPU clock speeds available in the pre-release Gigabyte BIOS, it was not possible to test overclocking thoroughly. We were able to reduce multipliers and easily reach 250FSB, which was the top speed available in the pre-release BIOS. However, until we receive the updated BIOS, we cannot determine the full overclocking capabilities of the K8NXP-9.

Since there have been many reports of issues with memory on the earlier Gigabyte nForce3 Ultra, more effort went into testing memory performance on the K8NXP-9. Our memory stress test measures the ability of the K8NXP-9 to operate at its officially supported memory frequency (400MHz DDR), at the lowest memory timings that OCZ PC3200 Platinum Rev. 2 modules will support. All DIMMs used for stress testing were 512MB double-sided (or double-bank) memory. To make sure that memory performed properly in Dual-Channel mode, memory was only tested using either one dual-channel (2 DIMMs) or 2 dual-channels (4 DIMMs).

Stable DDR400 Timings - One Dual-Channel (2/4 DIMMs populated)
Clock Speed:	200MHz
CAS Latency:	2.0
RAS to CAS Delay:	2T
RAS Precharge:	10T*
Precharge Delay:	2T
Command Rate:	1T

*Several memory tests have shown that memory performs fastest on the nVidia nForce chipsets at a TRas (RAS Precharge) settings in the 9 to 13 range. Memory Bandwidth tests were run with memtest86 with TRas settings from 5 to 15 at a wide range of different memory speeds. The best bandwidth was consistently at 9 to 11 at every speed, with TRas 10 always in the best range at every speed. The performance improvement at TRas 10 was only 2% to 4% over TRas 5 and 6 depending on the speed, but the performance advantage was consistent across all tests. All benchmarks were therefore run at a TRas setting of 10.

Using two DIMMs in Dual-Channel 128-bit mode, the memory performed in all benchmarks at the fastest 2-2-2-10 timings, at default voltage. As a further test, we ran every pair of PC3200 DIMMs that we had in the lab at their fastest timings, at DDR400 in DC mode. We had no problem with any RAM that we tested. It appears that the problems with Dual-Channel mode and memory compatibility, which were reported on the earlier Gigabyte nF3 Ultra board, have been improved greatly or eliminated on this nForce4 version.

Stable DDR400 Timings - 4 DIMMs (4/4 DIMMs populated)
Clock Speed:	200MHz
CAS Latency:	2.0
RAS to CAS Delay:	2T
RAS Precharge:	10T*
Precharge Delay:	2T
Command Rate:	2T

Tests with all four DIMM slots populated on the Gigabyte required a 2T Command Rate with 4 DIMMs in two dual channels. This is the pattern seen on other top-performing Socket 939 boards. However, an "Auto" setting for Command Rate would not boot, and we had to force a 2T setting in BIOS with 4 DIMMs. Once 2T was set in BIOS, there was no problem running 4 DS DIMMs at the same aggressive 2-2-2-10 timings we had used with 2 DIMMs.