My motherboard (Asus A8N-SLI Deluxe Socket 939) currently has Geil 2x512MB Dual Channel ram, using DIMM_A1 and DIMM_B1, but windows will not boot after I installed a new single 1x 1GB DDR400 Hynix ram stick on either DIMM_A2 or DIMM_B2. Since I already have dual channel installed must I have another 2x 512MB dual channel pair on DIMM_A2 and DIMM_B2 to upgrade to 2GB?