might be ur mobo, get dfi to get a clear look at everything, cant go wrong, something is wrong, u ram and psu is even better than mine
i think ur mobo is also wasting the timing on the ram, 238 @ 2-3-3-8 on rev 2 is kinda slow, (i have my cheap 2*1gb plat running at 234 bus @ 2.5-3-3-6, rev 2 has got to do betta than 2-3-3-8 @ 4 mhz higher)
check the voltage, evp @ 2.9, so do 2.8 on a dfi LP mobo with +.03 enable to get it to run at 2.88
check everything else first tho, i really think it's the mobo