I have a strange problem with DIMM D1 slot. I recently bought a box of DDR4 quad channel memory that are listed under Asus X99 Memory QVL list. *

If I insert a single ram into D1 slot (default first slot by manual), I get an error code 53 - i.e. no memory module detected. The same error occurs if I used other brand of DDR4 stick. *

*If I insert 4 memory sticks into A1 B1 C1 D1 (XMP disabled), then both BIOS and Windows only see 3 of them *all except D1; however, under HWINFO64, it reports all 4 DIMM SLOTS and shows "Quad Channel" -- and shows the SPD values for all four sticks. But aida64 reports Triple-Channel Memory.

How do i get windows and BIOS to see all the 4 sticks? If I try to overclock it or set XMP enabled in BIOS, it goes thru a tuning process and cant boot because its trying to overclock the slot that it doesnt see but cant, so I get "overclock failed" error on the next boot.

If I insert 3 sticks, except D1, then it boots up and overclocks the RAM without issue. Windows and HWinfo64 both reports triple channel memory with 3 sticks.

All four sticks are working because I've swapped them around in the 3 channel configuration and made sure each one works. *

Is this a problem with my D1 DIMM slot? *Could this be caused by bent cpu pins? I took cpu off and looked but I don’t see any obvious bent pins but I can’t be sure.

When I seat the cpu I notice it’s not fitted in fixed, there’s a little room to move around while it’s in the socket, is this normal? How should I best line up the cpu in the socket?

* Thanks, in advance.... *this is driving me nuts. This system is otherwise usable with triple channel RAM.*

Another issue, not sure if related. When I did a memory speed test with hwinfo64, memory read speed *is much higher than write speed, like 58000 vs 35000. The write speed increases to about 43000 if I increase cpu cache frequency but it’s still a discrepancy...*