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x399 taichi doesn't recognize all the ram

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Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
Printed Date: 25 May 2024 at 7:33pm
Software Version: Web Wiz Forums 12.04 -

Topic: x399 taichi doesn't recognize all the ram
Posted By: af13
Subject: x399 taichi doesn't recognize all the ram
Date Posted: 31 Jan 2019 at 8:15am
We are having the same problem as this post:

However, the solutions don't seem to be working for us.

We are building two identical machines with the following:
x399 taichi
2950x threadripper
64GB ram (4x16) (Corsair CMK64GX4M4A2400C16)
750w psu
gtx 1070ti
960pro m.2 nvme ssd

Initially, neither machine would boot and after a combination of updating the bios to 3.5 and re-seating the processors, we did get them to boot. We also did not tighten down the frame around the processor as tight the second time after reading something about it somewhere. However, after booting, machine 1 was only recognizing 32gb of ram in both the bios and windows (ignoring the ram in c2/d2 slots) but still running in quad mode. Machine 2 was only recognizing 48gb of ram in both the bios and windows (ignoring the ram in c2). We moved the ram around in to different patterns and machine 1 never recognized any ram in the C or D slots, while machine 2 refused recognize any ram in the C slot.

We re-seated the processor in machine 1 once again and once again the c and d slots weren't recognized. We tried adjusting the tension on the screw holding down the processor... tightening it made the machine not boot, and loosening it made only the B slots work.

We have not adjusted any timings, voltages, or made any changes within the uefi. Everything that was on Auto, still is on Auto.

So my questions are:

1. Are these processors really THAT finicky that you need the ideal amount of tension to hold down the processor or it won't run properly? In 10 years of building computers, I've never had anything like this happen.

2. I know the ram is not on the mobo qvl, but we have seen that it was approved for the threadripper. Could it just be the ram? We are fairly sure there aren't any bad sticks, but maybe it just doesn't like the combinations? Also, I know 2400 is not ideal and faster is better... but this was purchased before I had a chance to review and we thought we'd give it a shot. But, if it's going to not recognize it and/or not boot, then we should just return it and get something else.

3. Do you think it's possible we got two bad motherboards? Being that we are having the same problems with both makes me feel like we're doing something wrong. It seems unlikely that both would have problems. But, it could just be a bad batch or something and maybe the processor trays are just out of tolerance or something. BTW, these are the Lotes trays, not the foxconn ones that people have had problems with.

Any help or tips would be appreciated!            

Posted By: af13
Date Posted: 31 Jan 2019 at 10:51am
D'oh! I'm going to leave this post up in case it helps somebody one day cause I just got it working after seating the processor for the 4th time, but using this guy's method:

I must have been tightening the chip down so it wasn't laying perfectly flat and maybe it wasn't making contact with some pins? I'm surprised it would work at all if it didn't have good contact. I'd assume it'd be all or none.

Posted By: Xaltar
Date Posted: 31 Jan 2019 at 2:31pm
Whenever memory banks are not working the first port of call is always to check the CPU installation The IMC has been located on the CPU for quite some time now, this most people know. What a lot of people don't realize is that the IMC is not connected to the board by a single pin, it's data paths are scattered throughout the CPU's pinout. Most commonly when a DIMM slot is not recognized there is a lifted corner on the CPU. Threadripper in particular is susceptible to this problem given it's huge size and large number of pins. AMD did well working with their partners to design the socket for it but you can still have issues with unbalanced pressure when installing. Thanks for sharing the vid, I hope it helps others with this problem


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