i've seen a lot of posts on various forums about twinmos not working well in nforce2 chipsets (the abit NF7 S more than others)
the strange thing is i have 2*256mb twinmos in my nf7 s running at 210fsb :S
i'll bought some twinmos pc3200 last night to stick in my SN41G2 - i'll let you know if it's the same :S