buying more RAM, question about pairing

[mitzibishi]

ok ive forgot most of what i knew so i need a little help.

i have 4gb of RAM:

DDR2 800mhz
2x CM2 x 2048-6400C5

5-5-5-18 @ 1.8v

i fancy another 2 sticks and am trying to get the same timings but most of the RAM im finding has a different voltage say, 1.9v or 2.1v.

does it matter if the voltage is different or would it be best to hold out and match the voltages aswell?

and what about versions? i should think version shouldnt matter at all.

i plan on overclocking soon so would any of the above being different to my RAM effect overclocking.


would this ram be ok to pair up with my 4gb?

http://www.auctiva.com/hostedimages/showimage.aspx?gid=447103&ppid=1122&image=522694641&images=522694641,522694725,522694795,522694852&formats=0,0,0,0&format=0

 

[Plec]

Voltages are important as some sticks will require the full rated voltage to run at spec - but timings can be matched if they're being dropped/raised within spec.

If your not buying second hand then the Crucial Ballistix Sport 4GB (2x2GB) DDR2 PC2-6400C5 800MHz Dual Channel Kit should slot nicely in place with very little tinkering...

Additional:

would this ram be ok to pair up with my 4gb?

http://www.auctiva.com/hostedimages/showimage.aspx?gid=447103&ppid=1122&image=522694641&images=522694641,522694725,522694795,522694852&formats=0,0,0,0&format=0

Not sure - a quick google has given up 2 voltages - 1.8 and 1.9V.