I am about to buy the MSI Z77A-GD65 ... And was woundering what RAM voltage is optimal for it ? 1.5V , 1.65V ? and will it work with any latency or CAS ?
Yes, you will want to get 1.5 volt DDR3. An 8GB kit of 2 dimms will run $26-$50.
Lower latency is good, and more expensive. CL9 is common at the lower price range.
If you are NOT overclocking, DDR3 1333 or 1600 will be fine. No point in spending more money for bigger numbers.
Please consult the .pdf memory list you will click on from this page: http://www.msi.com/product/mb/Z77A-GD65.html#/?div=TestReport
Experts can make lots of other memory work. But given the question you are asking, stick with a part number that is on this list.