GA 7N400 Pro2 ram timings with XP3200 (400mhz)

Hi All
Ga 7n400 pro2 with XP3200+ (400fsb)
2* 256 PC3200 (DDR 400) Kingmax Ram
Gigabyte FX5600XT
IBM 40GB (C: pri ma)
Pioneer DVD Rom (pri sl)
LG 4081B DVD multi write (sec ma)
Samsung spinpoint 160 GB (sec sl)
TDK CD writer - on Gigagraid ATA

Having upgraded CPU from an XP2800 (333 bus) to XP3200 (400 bus) and changed
BIOS settings all to "normal or auto where poss, the system booted normally
but was extremely unstable, crashing straight away or within 10 mins or so.
Trying allsorts of BIOS options to cure this, I found that using user
settings and 200 fsb, but using the RAM frequency set at 83% (333) I find
the system perfectly stable again.
I bought the Kingmax RAM because it was on the "recomended" list for my old
GA 7VAXP which blew a power transistor aged 18 months and died. I did look
on the NVIDEA site and noticed that Kingmax RAM is not on their reccomended
listfor nForce 2 chipsets. DUH!
Is it possible that this RAM is incompatible and running it at 333 is my
best hope?

Thanks

CP