hello, right now i have the G.SKILL Ripjaws X Series 4GB DDR3 1600 CAS latency 6 installed in two slots. If i add a second pair for a total 8GB will my performance be affected in any way? Or should i just by 8Gb pair in one set? Thank you for any help win72500k 3.3 GSKILL DDR3 1600 4GB GTX 570 Sound Blaster x-fi win7x64

It may help a little but FSX only uses 4GB. The extra 4GB would help for background tasks like antivirus and windows explorer and leave a full 4GB for FSX.

First I would check how much memory is actually being used during a flightsim session. You can do that with the resource monitor that comes with windows. If you are nearing the 4 GB, having more could be beneficial.Generally speaking, AMD and Intel both prefer having only one set of DIMM's, at least it has been so in the past and I've read that it is still the case. Depending on your current memory settings you might need to loosen the timings in the BIOS for 2 sets of DIMM's to work and that will influence the performance. I have no idea how big the impact will be though, it might be small.