Since this was our first chance to test two identical SLI-capable videocards together, we decided to overclock the cards only in SLI mode. That means we're raising both the core and the memory frequency of both cards at the same time when moving the sliders. As usual we started with the core first which was clocked at 500 MHz by default on both cards.

Remembering our results with the Gigabyte GV-3D1 videocard, we didn't have high expectations for SLI overclocking, so we started out slowly. Surprisingly this pair of MSI NX6600GT-TD128E videocards seemed up to the task, and we were easily able to pass 530, 540 and 550 MHz! In the end we were able to run both GPUs at 563 MHz with stock cooling; not bad at all!

After having such good results with the 660GT cores we were hoping to duplicate that success with the memory as well. Starting at a stock 1 GHz and moving up in 5 MHz intervals we had some decent success here too. With the 2.0ns Samsung GDDR3 memory that both cards employ, we were easily able to pass the 1.1 GHz mark and the memory topped out at an impressive 1130 MHz! Definitely not to shabby.

It's nice to see that there still is headroom for overclocking, even if you run SLI.

PCStats Test System Specs:

processor: amd athlon64 4000+ clock speed: 12 x 200 mhz = 2.4 ghz motherboards: gigabyte ga-k8nxp-sli (nf4-sli) gigabyte ga-k8nsnxp-939 (nf3 ultra) videocard: msi rx800xt-vtd256e powercolor x700 pro albatron trinity geforce 6600gt agp msi nx6600gt-td128 albatron trinity pc6600 gigabyte gv-3d1 (single mode) gigabyte gv-3d1 (sli mode) msi nx6600gt-td128e (single mode) msi nx6600gt-td128e (sli mode) memory: 2x 512mb mushkin pc3200 l2 v2 hard drive: 40gb wd hdd cdrom: aopen 52x combo powersupply: seasonic super tornado 400w software setup windowsxp build 2600 nforce catalyst 4.12 detonator 66.93 benchmarks 3dmark2001se 3dmark05 codecreatures aquamark aquamark3 gun metal 2 x2 the threat ut2003 doom3 aa test, af and aa+af test 3dmark2001se ut2003

the agp and pci-e systems use a different motherboard but results are shown for reference.