I have just bought the AS Rock Extreme 3 970 and it has four slots for ram. I already have two sticks of Kingston Hyperx Red 4gb, and my friend is offering me Corsair XMS3 4GB RAM sticks. Can I use his RAM in my computer?
In most cases, yes. The motherboard (if set to AUTO in the BIOS) should match up the speeds/settings of the differing memory with no issues. Typically, they will run at the slower settings of the 2 brands. From a performance standpoint, you should see little or no impact.
It's best just to get 1 set of DRAM in the amount you want, mixing sets, even of the same exact model can often be problematic,,,,see this problem daily here at Toms and other forums, mixing back with DDR and DDR2 wasn't so much problematic as there were basically just set parameters, but todays DDR3 is all over the place with timings voltages, etc, different ICs in use and DDR3 is made to much higher tolerances