huh, didnt know 4GiB modules were made for DDR2. My nforce 790i sli ultra board only supported 2GiB maximum per stick and it was DDR3.
anyways, maybe you're giving too much volts. My friend's computer started getting BSODs, did some tests, it was the RAM. I pushed more volts, the problem got worse. so I instead undervolted and all the memory-related errors went away.
You probably aren't going to be worried overclocking on such an old platform. I suggest just sticking to the JEDEC specifications. 400MHz (800MHz DDR) with 6-6-6-18-24 timings at 1.8 volts. If you still get problems, try less sticks until you're stable. if you aren't stable with 1 stick, then you need to adjust RAM specific settings/volts (try a slower JEDEC speed). if you are stable with less sticks, its your memory controller, so adjust your memory controller settings accordingly.
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