Assuming, you started running memtest86+ on the RAM at the stock settings, no errors are acceptable. Isolate your bad RAM and RMA it. If you end your testing/re-testing at stock with two good sticks, you could begin OCing it incrementally with increases to the bus speed. When you get to faster settings that won't POST, increase the volts in small increments to get to POST. After POST, load to memtest86+ using a USB stick, CD, or floppy. If no errors, try higher freqs (speed) on the RAM until you get the RAM freq stable (no errors in memtest86+) at the speed you want.