I got 3 new RAM Modules (CSX 4GB DDR3 1333MHz) if I insert one Module into my ASUS Z8NA-D6 Board the Computer starts. But if I insert a second or third one the Computer wont start. Next I run a memtest for each module but all works fine for one Module.
The Board has a triple Chanel Controller and DDR3 RAM is dual Chanel but it doesent matter I think?
What I do wrong?
There are two causes for this problem. One is if the slot is damaged somehow or there is debris or dust in the slot. But the most likely cause is improper CPU insertion.
Check the slot first because that's the easiest thing to do. If you see any debris or damaged pins, that's your problem.
If the slot is perfect, you need to remove the CPU. Inspect the contacts and, if any are bent or damaged, very carefully straighten them with a toothpick. Reseat the CPU making sure to lower it straight down. Replace the thermal compound and then mate the heat sink to the heat spreader.
According to the spec there are 6 slots, meaning 3 channels per cpu:
Total Slots : 6 (3-channel per CPU, 3 DIMM per CPU)
While usually you can encounter "mechanically double sided" (x16 organization) modules to occupy two slots, that should not happen accross different channels if they are all the same.
Some memory controllers are very picky: use same memory modules for all slots. E.g. they don't like using a mixed configuration of single-sided and double sided DIMMs (as their memory chips have a different internal layout). Others are less picky but require a certain configuration.
Check your Motherboard BIOS version and then install latest version of BIOS from this Link.Your problem will be solved.
