RAM HELP. voltages and now strange cpu problem

[my_computer]

Hi. i recently had a problem with my computer and the man who repaired it gave me 1gb of ram to keep me going until i got my previous ram replaced. I checked the bios and it said it was running at 1.80 v. when I received my previous ram (geil 2gb), it said on the pack it needed 2.1v. so tonight thinking maybe i'm not getting the most out of my geil 2gb ram, i decided to check the 1gb that the man had given me, to see if it said the voltage on it in the way that the geil does. i didn't see anything but the sticker said

DDR2-512 pc5 300 667MHZ 206639

I put the ram back in and my computer wouldn't start up. i removed the ram and tried just using my geil ram. it started up but i got the message


CPU is unworkable or has been changed. please recheck cpu softmenu.

i turned off the computer and put back the ram that the man had given me. this time i switched on and it was working but i am still receiving this cpu message.

so my questions..
1) is it possible to have my 1 gb that the man gave me which is currently running at 1.8v. whilst having my 2gb geil ram running at 2.1v ?
2) why has this cpu message appeared and what do i need to do to fix it?

my cpu is the Intel core 2 quad q6600 @240GHz

looking forward to hearing all your wisdom

edit: I'm googling and seeing that loading default bios settings can help. and something to do with cmos that i don't understand.
I'm also reading that my lower voltage ram may be slowing down my other stuff. and the different ram cannot be set with separate voltages. but i'm not really sure about this either. I'll wait for someone with brains before i go messing.

 

[my_computer]

i think i'll leave the ram alone then and maybe get another 2gb of geil rather than do anything silly. in the morning when i startup i'll reset to defaults in bios. the repair man wont have set anything strangely will he?
also would it be better having 3gb at 1.8v or 2gb at 2.1v?
and...thanks for your help

 

[my_computer]

i dont think i really need 3gb i play some games and thats about it. i suppose crysis is most demanding and it was running fine with 2gb
i'm using 2x 1gb of geil and 2x 512 from the repair man
i've been running games fine with my 3gb running at 1.8v
so no i dont really have any problems. i'll probably just leave things how they are until i get another 2gb of geil (even though i dont need it... its cheap and i would like to have all my ram running correctly)