Right now I'm using a MachSpeed motherboard with 4GB of memory in a 4 X 1GB configuration. It will only recognize 2.5GB of that memory. I have ruled out bad memory by booting numerous times using single and multiple modules. When I boot with 3 modules the post-up shows 2621440K of memory. With all 4 modules it will also only show 2621440K of memory. MachSpeed techsupport tells me that I "should" see 3GB at most but they're stumped as to why I see only 2.5GB. They tell me that because of bandwidth, I would need to use 2 X 2GB memory modules to see all 4GB. I'm now seriously considering just replacing the board with an ASUS P5-D motherboard. I'm wondering now though if this is a common problem when using 1GB memory modules and the problem will possibly follow me to another motherboard.