Question 3 New GB Z690 UD AX DDR4 but only one has bad DIMM slots A1 & A2. B1 & B2 work just fine

Jul 3, 2022
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This past week I put together three new machines with Gigabyte Z690 UD AX DDR4 and an i9-12900K in each of them. The first two came up perfectly. The third one won't even get past post if a working DDR4 DIMM is put into either A1 or A2 slots. Both B1 and B2 work just fine on that and I have installed Windows 11 Pro on all three.

All four of my DDR4 DIMMs work just fine. My research says check the CPU and DIMM pins. I have reflashed the Bios to F7b, but the board won't exit post.

Any Thoughts or suggestions?

-david BTW
 

Lutfij

Titan
Moderator
Welcome to the forums, newcomer!

It could even be that one of the memory channels(channel A) on the processor might be bad. Might want to inspect the CPU socket for any bent or broken CPU socket pins. Also, you could drop the processor into the other known working board to rule out your theory that one out of the 3 boards has faulty ram slots.
 
Jul 3, 2022
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Welcome to the forums, newcomer!

It could even be that one of the memory channels(channel A) on the processor might be bad. Might want to inspect the CPU socket for any bent or broken CPU socket pins. Also, you could drop the processor into the other known working board to rule out your theory that one out of the 3 boards has faulty ram slots.
Thanks. My builds have high cooling fans that are a pain to remove but I guess I will do so on one of my others. I will also inspect the pins on both the cpu socket and Dram sockets

-davebtw
 
Jul 3, 2022
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I took my third machine apart, removed the cooler and pulled the CPU very carefully. I have a full SMT rework set of tools including a really good stereo microscope. I inspected the DIMM connectors and soldering on all slots and there are no bent or corroded pins anywhere. The soldering on the DIMMs were clean and solid.

I then inspected the LGA-1700 socket and every pin looked unbent and good zoomed in to max! IT takes a while to inspect every pin on an LGA-1700.

Then I looked at the bottom of the CPU. There was no thermal compound there at all and it looked clean at first. I could see small scratches on the pads where the socket pins made contact. But after closer inspection it appeared not to be as clean as I had hoped. I used some industrial grade cotton swabs and Deoxit Pro Gold (Has a different name now, and scrubbed the entire contact side of the cpu. There was some dust, but on some pads they looks a little bit dirty.

After cleaning very carefully, I reassembled the machine and now all the memory slots work perfectly. I think there must have been some bad contact between the pads and the socket contacts.

I would caution anyone to not try this at home unless you have the proper tools as damage to the fragile socket pins could easily occur.

I am quite thankful that I do not have to disassemble a second computer to check the CPU, worry about getting a replacement motherboard. What a pain that would have been.

Thanks for the suggestions. It helped me work through the troubleshooting sequence in my mind overnight.
 

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