I've just replaced the Asus P8H67-M PRO/CSM motherboard in my computer, and now there is boot failure. Nothing appears on the monitor, and an LED labeled "DRAM LED" illuminates steady red. Pushing the "Mem OK" button causes the system to restart, and the same thing happens. I've tried removing all but a single DRAM module, and testing it in each of the four memory slots, with the same result. I've tested the other memory modules, as well, with the same behavior. All four memory modules worked earlier today in the motherboard which I needed to replace, which is an identical board. I replaced it because a PCIe slot stopped working, and so did the Ethernet controller. The memory modules are Corsair PC3 12800 1600 DDR3 4GB 240-Pin. The motherboard literature says the DRAM LED illuminates if memory is incompatible with the board, which doesn't seem to be so.
One other observation: there are four DRAM LED's, arranged in a straight line, and the one which illuminates is on the end. I believe this means that it corresponds to either the first or the fourth memory slot. However, that LED illuminates even if a single memory module is installed in the 2nd or 3rd memory slot, and the two slots on either end are vacant.