I have to ask the Pros

A friend of mine has a mixed bag of ram in his computer,he has a NF7-S and all three slots are being used,1st slot is 512 of Corsair PC3200LL,and next to it is 256 Twinmos C2.5 and the same in the dual mode slot,and the thing is it is running 212X12 with no problems,he says anyway,I was there 2 hours while he soldered something onto my board,and Prime ran all that time with no problems.I couldn't believe it,I was always told not to mix ram like that..
I just had to pass this along

hm,why shouldnt it run,if all ram modules are good at 424 mhz?

I may give it a shot and see