Got myself my X300 the other day and set it all up with my 4650G, Crucial Ballistix BL2K16G32C16S4B 3200MHZ (2x16), 2TB SSD, and noctua LH9a AM4 cooler.
Turn it on, fans speeds up but can't get into POST - at most i see a amber blinking light. Probably will try the stock cooler as well, but...