memory vs. video card problem-expert needed

[5t3ph3n 0]

About a week ago i added 128 sdram in my box and now i'm with 224 mb ram. Very oddly about the same time (i, honestly am not sure exactly before or after) i started getting random hard locks and some pixels distortion. I ran SIMMTESTER's DOCmemory and in 64 loops it found zero problems. So i figured out it must be video card problem so i plugged in a new AGP TNT2 32MB from Pine on Friday. The problem is that yesterday night another hard lock occured! Any ideas (memory, video or both can cause hard locks?)?

 

Abit BH6 rev1.0 latest BIOS/setup defaults -ACPI enabled

Pine M64 Riva tnt2 w/ 32mb @ AGP +latest official detonator 6.31 drivers (which i also used before w/ my canopus spectra 2500tnt with zero probs)

dimm1: 32mbsdram/100 , dimm2:64, dimm3:128

 

P.S. I never had any hard-lock before

 

thanks in advance + sorry for the long post