Ive got a different motherboard, so not exactly sure what yours would be labelled, but on my Abit IP35 Pro its called DRAM Speed (CPU : DRAM) which was set to 1.5 originally, but ive put it down to 1 to underclock it while testing my CPU. Your mobo may give you the ratio 2:3 , be called FSB : DRAM.
Basically this ratio is used to generate the RAM speed by taking the FSB speed, in your case 356, and then multiplying it by this ratio, 2:3 which is 1.5, resulting in your 534.
By adjusting this to 1:1, you will under clock your RAM to be the same as the FSB (356) and thus illiminating it from causing issues/errors in prime. Once you've found your max stable CPU speed, you can then start clocking your RAM back to stock speed and above.