DIMM Slots 1 & 2 Always Fail
Printed From: ASRock.com
Category: Technical Support
Forum Name: Intel Motherboards
Forum Description: Question about ASRock Intel Motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=11086
Printed Date: 06 Aug 2025 at 4:34am Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: DIMM Slots 1 & 2 Always Fail
Posted By: unconquerednole
Subject: DIMM Slots 1 & 2 Always Fail
Date Posted: 12 Mar 2019 at 4:47am
Hey Folks,
This has been a real headscratcher for me and is approaching the point of frustration.
Build is Z390 Phantom Gaming 6, I9-9900k, and G.Skill TridentZ RGB RAM. The configuration I am attempting that always results in fail to reach even BIOS is 4x8. Model is F4-3200C16D-16GTZR, DDR4 3200 CL 16-18-18-38 1.35v 8Gx2 Intel XMP 2.0 Ready.
I checked the compatibility page and confirmed ASRock indicates that model should work in 2/4 setup.
What I've tried: I previously had ordered the Z390 Taichi Ultimate and was running into the exact same issue. Slots 1&2 never work, not with 1 stick, not A1 & B1, not A2 & B2, not reseating, nothing. If a stick goes in 1 or 2, PC never boots. Only slots 3 & 4 work with all 4 sticks, so the RAM isn't failing. 3 & 4 always work and PC boots fine. I tried flashing BIOS, no effect on getting slots 1 & 2 to work. I double checked the compatibility for the RAM on ASRock's support page and realized the Taichi Ultimate only listed "2" as opposed to 2/4, however, I would have thought the 2 would at least be dual channel. 3 & 4, or B1 & B2, is single channel memory mode.
So I returned the Taichi Ultimate and picked up the Z390 Phantom Gaming 6, because horray, the compatibility shows 2/4 for this RAM. Tried exact same steps as previously, slots 1 & 2 never work again.
Other things I've tried: the cooler isn't too tight, the CPU doesn't appear to be damaged, and well, 2 different boards and I haven't noticed a bent or broken pin.
PC does work normal and as expected with the RAM in slots 3 & 4.
Stuff I haven't tried: Trying new RAM, trying new CPU, and rolling back the Windows Update that has caused a bit of headache for folks but my understanding was the Windows Update has no impact on RAM, RGB or not.
Of note, with all 4 RAM sticks in, the LEDs do illuminate all 4 sticks even though it'll never boot.
The Dr. Debug code cycles 00/4C with all 4 RAM in, and did on both boards.
I know its possible to get a bad CPU but the chances aren't great, and the PC runs great otherwise.
Any help would be greatly appreciated.
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Replies:
Posted By: grandmathter
Date Posted: 09 Apr 2020 at 5:42pm
Using a setup almost exactly the same and encountering the same issue.
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Posted By: Xaltar
Date Posted: 09 Apr 2020 at 6:19pm
Return that CPU if you can, 2 boards, same issue means there is a high chance the IMC (memory controller on the CPU) is faulty. Defective IMCs have become quite common in recent years. If you search the forums for similar issues you will see most cases were resolved with a new CPU. In the cases where the board was to blame, replacing it solved the issue. You have used 2 separate boards and the issue persists.
It sounds like one of the memory channels on your IMC is dead.
Dual channel: A1, B1 = Channel 1 A2, B2 = Channel 2
By having multiple separate paths to the CPU you increase bandwidth and hence performance.
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