So I am currently running my pc on Vista32bit with 4gb ram(2x2). I am going to upgrade to Windows 7 64 bit, and would like to use another 4gb ram(2x2). Would it be worth it to add second set of 2x2 ram to it? Totalling 8gb, would there be any conflict between the two? As long as all their settings were the same wouldnt they be ok? I do have to set both pairs manually to ddr3 1600 in bios.
??? -- IF the Current RAM is cheaper and still available why not just get another set of identical modules and avoid any possible incompatibilities ? --- The 2 sets will most likely work together but there is the possibility that the chips used on them will be from different makers (since G-skill buys memory chips from several companies) and there may be slight differences that could cause some instability.
Since you have the 2 sets already it can't hurt to try them together (chances are they'll be fine since both are 1600 CAS9 @1.5V) - If it were me I'd use them and just keep on mind that if stability issues arise that I might need to make some adjustments to speed or timings to find the balance where they both work properly together - doesn't hurt to try and usually there are not any problems with such closely spec'd modules and they may actually be the same modules with a different heatsink applied anyway.
I'm actually running 2x1GB OCZ platinum rated at 1333 7-7-7-20 1.8V alongside a 2x1GB Crucial Ballistix DDR3 1800 8-8-8-24 @1.9 -- Since the Crucial were no longer available (got them for a really good price but crucial discontinued them ) and OCZ had a good sale when I was buying a second set ---- Am running them both together at DDR3 1333 7-7-7-21 -1 @ 1.8V because this was the setting they both ran well at with no stability issues and the fastest throughput (I've also run them at DDR3 1600 8-8-8-24 for awhile but the system performance is better at 1333 7-7-7-21 than it was at 1600 since the memory controller on my PII x3 720 prefers 1333Mhz.)
So you should not have problems but there are times where you will but that usually just means a little tweaking is needed to get them working together correctly (just have to find the fastest timings they will both run stable at which can take some playing with at times!)
Trust me get a second Set of what you ALREADY have installed. Yes, I can read the specs, but what you don't see are the different IC's. I am not saying it won't work, what i am saying there's nothing but 'down side' to mixing.
If 'anyone' wants to risk errors by mixing then that's their business to do. It's ill advised.