Dual Channel Issue

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   It makes perfect sense, a faulty/intermittent IMC, given you have tried different
boards and RAM, is the only component that can cause the symptoms you describe.

If it was RAM, that would mean you used 2 completely incompatible model kits. Even
then, they should have worked at 2133 in dual channel. The IMC is not a simple
circuit, it relies on voltage etc the same as the CPU and is also required to 
run out of spec in order to achieve XMP frequencies.

You can try raising the RAM and related voltages by 0.01v then 0.02v up to 
0.05v and see if that stabilizes the RAM in dual channel. There are numerous 
tutorials out there on RAM overclocking and what voltages are related. However, if
this works then your IMC is definitely not working correctly. The reason I say 
RMA the CPU is because intermittent can suddenly turn to completely dead.

You can also carefully check and clean the bottom of the CPU, dirt or residue on
the contact pads can cause the issues you are describing too but if that were the
case, it would be the same RAM channels not working on both boards (A or B).

I know it's inconvenient but it could save you a lot of headaches down the line.
If I am correct, and I strongly suspect I am given similar issues here on the 
forums in the past, the IMC is not functioning correctly and could die on you
completely in time.

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Xaltar Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 16 May 2015 Location: Europe Status: Offline Points: 23198	Post Options Post Reply Quote Xaltar Report Post Thanks(0) Quote Reply Posted: 15 Jul 2020 at 2:31am
	It makes perfect sense, a faulty/intermittent IMC, given you have tried different boards and RAM, is the only component that can cause the symptoms you describe. If it was RAM, that would mean you used 2 completely incompatible model kits. Even then, they should have worked at 2133 in dual channel. The IMC is not a simple circuit, it relies on voltage etc the same as the CPU and is also required to run out of spec in order to achieve XMP frequencies. You can try raising the RAM and related voltages by 0.01v then 0.02v up to 0.05v and see if that stabilizes the RAM in dual channel. There are numerous tutorials out there on RAM overclocking and what voltages are related. However, if this works then your IMC is definitely not working correctly. The reason I say RMA the CPU is because intermittent can suddenly turn to completely dead. You can also carefully check and clean the bottom of the CPU, dirt or residue on the contact pads can cause the issues you are describing too but if that were the case, it would be the same RAM channels not working on both boards (A or B). I know it's inconvenient but it could save you a lot of headaches down the line. If I am correct, and I strongly suspect I am given similar issues here on the forums in the past, the IMC is not functioning correctly and could die on you completely in time.


geekerator Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21 Oct 2020 Location: 78015 Status: Offline Points: 1	Post Options Post Reply Quote geekerator Report Post Thanks(0) Quote Reply Posted: 21 Oct 2020 at 4:40am
	Same problem here (no dual channel operation - BUT single channel using B1 & B2 for the memory works perfectly throughout all the hardware replacements cited below), except I have gone through many more steps: replaced the MB, then replaced the CPU and memory, then replaced MB again. Finally, shipped MB+CPU+memory to ASRock for diagnosis. ASRock tech said CPU MUST BE DEFECTIVE, so they are sending the whole mess back to me again for a third CPU replacement. How likely is it that 3 CPUs, 2 sets of memory, and 3 different MBs all exhibit EXACTLY the same symptoms. Also, all PSU pins have been probed with a bench voltmeter and were right on spec. System is Z490 Taichi, i9-10900K, 32GB DDR4-3600 memory with nothing else installed (i.e., its on the bench).

Jokergod2000 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 08 Jan 2021 Status: Offline Points: 2	Post Options Post Reply Quote Jokergod2000 Report Post Thanks(0) Quote Reply Posted: 08 Jan 2021 at 11:21pm
	Oh god, I have the same issue. Replaced RAM and MB, working on an RMA for the CPU now. Anyone resolve this?

bow_bell Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21 Jan 2021 Status: Offline Points: 2	Post Options Post Reply Quote bow_bell Report Post Thanks(0) Quote Reply Posted: 21 Jan 2021 at 11:36am
	Any progress with this issue? I'm having exactly the same issue. Building a gaming rig for a friend using 2 sticks of Corsair DDR4 8Gb, i5 10400F and a Z490 board and only was I can get it to work is to put the sticks in channel B. If I put any sticks in A it does not boot.

Xaltar Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 16 May 2015 Location: Europe Status: Offline Points: 23198	Post Options Post Reply Quote Xaltar Report Post Thanks(0) Quote Reply Posted: 21 Jan 2021 at 11:41pm
	As a general rule, with modern systems, if you have a bad or completely non functional RAM channel RMA your CPU. About 90% of the time if you can't get RAM to work in one of your channels the CPU memory controller is dead/dying. Now if the RAM works in both channels but you are stuck in single channel mode despite having RAM in the correct slots for dual channel operation, make sure the RAM is fully seated. The RAM not being all the way seated is almost always behind missing dual channel when the RAM is in the correct slots (A2 and B2 or all 4 slots).


bow_bell Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21 Jan 2021 Status: Offline Points: 2	Post Options Post Reply Quote bow_bell Report Post Thanks(0) Quote Reply Posted: 22 Jan 2021 at 4:40pm
	I've solved the problem: I discovered that dual channel worked if I removed the CPU cooler, I then inspected the motherboard CPU bed and discovered a couple of bent pins. (With the hinge for the CPU at the top the damage was top right corner, very edge). After straightening the pins using a sewing needle and magnifying glass (very good video on Linus Tech Tips about this) and hey presto the PC runs flawlessly! In summary dual channel now works after fixing bent pins on motherboard CPU bed (top right corner). There have been various other forum postings with similar issues especially after replacing the CPU cooler (eg Cooler Master Hyper 212) and accusing having too much pressure on the CPU.

Xaltar Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 16 May 2015 Location: Europe Status: Offline Points: 23198	Post Options Post Reply Quote Xaltar Report Post Thanks(1) Quote Reply Posted: 22 Jan 2021 at 7:32pm
	Glad to hear it Bent pins is another fairly common cause of missing channels though nowhere near as common as faulty CPUs these days. Excessive mounting pressure alone can cause the issue, even if the pins are not bent the CPU can warp causing some pins to make poor contact. I list this here for anyone finding this thread via search with similar issues.