not 100% its the mother board or the ram but i tried the ram 1 stick at a time and it ran fine. anyways, my computer has been running sluggish lately so i checked the basic stuff and saw that my ram was running in half, 4gig but (1.96 in use). also this, , i went into bios and it shows dimm slot 1 and 3 at 2048, enabled slot 1 2048 enabled slot 3 -, total memory size 2048. so somehow my slot 3 is disabled? i dunno how..what do i have going on here lol im not that awesome at computers haha

this isnt mine but looks pretty much the same minus the extra stick of ram:
GA-X58-UD3R Won't Enable 3rd DIMM Slot - Gigabyte - Motherboards-Memory
says something about a bent pin but i havent touched the inside of my computer since i built it or cleaning with air only and only lately ive been having this problem. thanks