Computer won't post with memory in DIMM slots A1 or A2. HELP!

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andrew.soteres

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Jan 1, 2018
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Computer will not post even to access the BIOS when RAM slots A1 or A2 are populated. The computer works fine when I have 1, 8 GB G.SKILL DDR4 stick in either slots B1 or B2, or if both B1 and B2 are populated. The BIOS shows that I have 16 GB DDR4 RAM installed if B1 and B2 are populated but of course it is on single-channel. WHen I try to put any combination of my two sticks of ram in A1 or A2, the computer turns on and fans spin, etc, but I have a black screen and the computer never even gets to the BIOS screen. Should I RMA it? I feel like I have a bad A1 and A2 RAM slots. Any input greatly appreciated.

Mobo: ASROCK Z370 Killer SLI/ac
CPU: I5-8600k coffee lake, stock (no OC)
RAM: 2x 8 GB G.Skill Aegis DDR4-2400 CL17
GPU: GTX 1060 6 GB
 
Solution
Darkbreeze
Nah, something is going on there. Are you saying you have another motherboard that is compatible with your CPU and memory? You sure about that? Is it a Z370 board too?

If not, then it's not compatible, at all. Only Z370 is compatible with coffee lake, for now at least.

My advice would be to RMA or return the motherboard, MSI and ASRock seem, to me anyhow, to always have a higher failure rate than ASUS or Gigabyte, so if they'll let you return the board for credit and go with something else you might want to seriously consider that. If not, at least a new board hopefully doesn't have the same issue.

If you replace the motherboard and you have the exact same problem still, then it's got to be a memory issue, but I really doubt it. When...
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Darkbreeze

Darkbreeze

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Maybe, but certainly not 99% sure. Not even close. To begin with you are not even populating the memory correctly.


The motherboard manual for your board SPECIFICALLY designates slots DDR4_A2 and DDR4_B2 as the two slots that are SUPPOSED to be used if only two modules are installed. Slots A1 and B1 should ONLY be used if you are installing more than two modules. Do THAT first, and then we can move forward from there.

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AND, before you even do that it would be HIGHLY recommended that you make sure you have the MOST recent BIOS version installed. Both CPU performance and microcode changes are addressed in the two BIOS revisions available for your board since the release version. You only need to install the most recent version however.

https://www.asrock.com/MB/Intel/Z370 Killer SLIac/index.asp#BIOS
 
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andrew.soteres

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Jan 1, 2018
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When I use A2 and B2, the computer doesn't post. When I use A1 and B1 it doesn't post. When I use A1 alone or A2 alone, it doesn't post. I've tested it with both sticks of memory. When I use B2 or B1 alone, the computer works fine. If I use B1 AND B2, the computer works fine, it shows I have 16 GB DDR4, but only runs in single-channel.

I also flashed my BIOS to v1.2, the most recent version on ASrocks website.
 
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andrew.soteres

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I just tried it again. Put the 2 sticks in A2 and B2, waiting for about 2 minutes, just a black screen. Forced the computer off by holding the power button. Unplugged, put the stick from A2 into B1, computer posted in about 5 seconds, CPU-Z shows DIMMS 3 and 4 populated, with 8 GB RAM each, but only in single channel. The BIOS recognizes B1 and B2 having RAM in it correctly, but just single-channel, and obviously I want a motherboard that gives me dual-channel DDR4. Whenever either stick is in A1 or A2, the computer doesn't post at all, the lights on my keyboard and mouse don't even come on, whereas the lights on the keyboard and mouse do come on when the sticks are in B1, B2, or both.
 
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Darkbreeze

Darkbreeze

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Did you buy this memory in a matched set or did you purchase them individually?

Have you tried increasing the memory voltage by +.05v to see if that jump starts dual channel operation? Might also try bumping the voltage with only one module in slot B2, then save bios settings, shut down, install second module in A2, try to POST.

If none of this works then either the modules are not matched/tested to operate together or there IS a problem with the motherboard.
 
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Darkbreeze

Darkbreeze

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Might also try installing modules in A2 and B2, with power unplugged from the wall, remove the cmos battery for 3 minutes, plug back in and reinstall battery and try to POST. Sometimes even after updating the BIOS it needs to be reset so that the hardware tables are fresh.
 
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andrew.soteres

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The memory was bought as a matched pair. I tried adding 0.05v but that also caused a black screen (i saw that on another thread as a possible fix). And honestly, adding/removing volts or any other advanced settings is pretty over my head. I fairly educated with some of this stuff, but messing with volts and timings or other detailed settings like that I have no idea what I'm actually doing, lol.
 
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andrew.soteres

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I will try this and report back. Thanks.
 
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Darkbreeze

Darkbreeze

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It's all good, those are just things that you CAN try. They are not necessarily things you should HAVE to do with only two modules that are not even really high speed modules. Those DDR4 2400 modules, with only two installed, should easily SPD and even XMP with no adjustments to the voltage, timing or latency, especially on that higher clocked K sku processor.

One thing you MIGHT want to make absolutely sure of too, because specific pins on the CPU correspond to specific channels on the memory, is pull the CPU (Which you'll have to do to RMA the board anyhow if it comes to that) and make damn sure there are no bent or even slightly out of place pins or pad contacts on either the motherboard or the CPU. One bent motherboard pin can cause a variety of heartaches such as what you are experiencing, or corrupted/no video output, etc.

The memory controller is IN the CPU, so it could definitely have an effect on the memory configuration and performance if something is bent or if there is an issue with the CPU itself, although problems with the motherboard are a LOT more likely.
 
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andrew.soteres

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Jan 1, 2018
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I tried removing the battery and putting the memory in slots A2 and B2, but same result, black screen, no mouse/keyboard lights etc. At this point, should I just return it to newegg for a replacement? Apparently I can't get a refund, and surely it's not the memory sticks right? And when I take apart the build and use my old Mobo as a replacement until a new board is delivered, even if there is a bent pin theres nothing I can do about that right?
 
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andrew.soteres

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Jan 1, 2018
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I also notice on CPU-Z under the memory tab, that the NB frequency is jumping between 800 MHz up to 1700, to 3000 to 4000 randomly while I type this and nothing else going on the background. The RAM is CL17 while the CAS# latency is listed on CPU-Z as 15.0 clocks, is that normal?
 
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Darkbreeze

Darkbreeze

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Jun 24, 2014
80,411
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176,790
Nah, something is going on there. Are you saying you have another motherboard that is compatible with your CPU and memory? You sure about that? Is it a Z370 board too?

If not, then it's not compatible, at all. Only Z370 is compatible with coffee lake, for now at least.

My advice would be to RMA or return the motherboard, MSI and ASRock seem, to me anyhow, to always have a higher failure rate than ASUS or Gigabyte, so if they'll let you return the board for credit and go with something else you might want to seriously consider that. If not, at least a new board hopefully doesn't have the same issue.

If you replace the motherboard and you have the exact same problem still, then it's got to be a memory issue, but I really doubt it. When you disassemble the system use a air of high powered reading glasses or a magnifying glass and check VERY closely to make sure there are no bent pins, because if there ARE, they will void the warranty. You'll want to very gently straighten them out. VERY. GENTLY. And if there are bent pins and you can get them straight without a lot of effort, it might even be worth reassembling to see if it works correctly afterwards.

There are only three things that can affect the dual channel operation as far as I am aware and that is the motherboard, CPU and memory. Any of those three could be the culprit and CPU and motherboard diagnosis is largely a matter of eliminating everything else first. I think you've eliminated everything except what we've discussed so I think the rest is up to visual inspection and warranty.

 
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Solution
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andrew.soteres

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Jan 1, 2018
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Ok. Thanks for your help. No, I don't have the same set up as this one, I upgraded from an MSI z77 mobo with i5-3570k sandy bridge and ddr3. Will just have to use that one until this one gets replaced.
 
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hollyjoel86

Feb 18, 2018
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Hi andrew and all others! I have the exactly same problem like you! Cant install in slot a1/ a2 but works fine in single channel slot b1 and b2. You solved the problem?

Alao have the z370 killer sli and 2 x 8 gb crucial ddr4 2666 ramsticks. Hope so much you guys can help me!

Greetings

Oli
 
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