I just upgraded my mobo (ASUS p5Q Turbo Pro).The technician used my 2 x 2 GB DDR2 ram but he also added my old (same specs, latency, brand - Corsair) 2x1 GB DDR2. So now i Have 6 GB. But the mobo user guide says "you may install varying memory sizes in Chanel A and Channel B. The system maps the total size of the lower-sized channel for the dual-channeld configuration. Any excess memory from the higher-sized channel is the mapped for single-channel operation"From what I read in various forums I believe I am loosing speed with this configuration. I intent to remove the 2x1 GB sticks and put the 2x2GB sticks in the recommended DIMM sockets for OCing (on my mobo the yellow sockets). Especially FSX doesn't use the extra memory and I have no application needing this amount of 6GB. ASE, RC4, FS Commander are all on another PC in my network.Is my understanding correct ?Roger

The more sticks of RAM you use, the lower your potential maximum overclock. If you value clockspeed, take those 1GB sticks out. Just so we're clear: 4GB RAM with a higher clockspeed is better for MSFS (or any game for that matter) than extra RAM and a lower clock.

If the timings and bandwidth are the same, there will be no difference if You do not overclock. When overclocking, the more sticks, the less stable the PC will be on particular settings. FSX likes mostly low timings. I even lower the rated bandwidth for lowering the latency.If You use 32bit system, I'd go for 2x2024 and sell the old sticks.

Thank you for your answers. It confirms what I suspected. The 2 x 1GB are now out. I relocated the 2 x 2GB to the advised ASUS socket. Yes the PC is OC.Now I just installed a new 500GB disk just for FSX. Now I will reinstall FSX following NickN road map.