make sure the dimms have clicked in there slots. on these mb there two banks per the mb guild a0 and a1. the banks are one red and one black dimm. make sure the ram in the same bank. also look at the end of the ser# on the mb. that tell you the bios rev of your mb. most times these mb bios are out of date. if your is way out of date 0802 or under. then the mb may be misisng the cpu and ram code to post. I would look at your mb see the bios# and then see if you can download the newest bios and use the usb flash back port and update your bios.