Memory channel A not working

[tom1234560]

Hello, I recently bought a mobo, cpu and RAM:

Gigabyte Z370P D3
Intel i5-8600k
Corsair Vengeance LPX DDR4 3000mhz 16GB (2x8)

The first mobo I received was faulty so I had another one sent to me. This time I decided to breadboard the mobo and install components one at a time, and everything seems to be working apart from channel A of the RAM sockets.

If I have both RAM sticks on the same channel (Channel B - Slots 1 + 3) the computer posts fine and enters bios but it is only using a single channel. If I put either ram stick in any of the slots on channel A (2 + 4) the computer refuses to boot with the long repeating beep code which means "ram is not installed correctly".

I've tried all 4 slots separately with a single stick of ram and again the computer boots just fine with 1 stick in a channel B slot. But if the stick is in a channel A slot, I get the same beep code error.

I've also enabled and disabled the XMP profile associated with my RAM and it has absolutely no effect.

I'm really hoping I've not received yet another faulty mobo, do you guys have any suggestions I can try before requesting a 3rd board from Amazon?

 

[geofelt]

I have seen three reasons for this; none of which is easy to fix.

1. Yes, indeed, the motherboard is again defective.

2. You have bent a pin in the motherboard socket.
This is considered as a user error and will not be covered under warranty.
It cost me $50 some years ago to send one back to Gigabyte for a repair.

3. The cpu is defective. This is most unusual, but it happened to me once. A very difficult thing to diagnose.
If you can test with another compatible cpu, you can rule that option out.

If you can, just return the motherboard to amazon and buy elsewhere.
I suspect you just got the same motherboard back.

 

[tom1234560]

Well as far as I know the CPU is fine because it boots just fine with the RAM in a channel B socket and enters bios with no errors. I have no other CPU to swap it with so there's no way to check that possibility unfortunately.

As for the mobo it's definitely not the same one again because I still have the original faulty one aswell, ready to be sent back 😛. It'll just be annoying having to get another one sent out.

 

[geofelt]

Well as far as I know the CPU is fine because it boots just fine with the RAM in a channel B socket and enters bios with no errors. I have no other CPU to swap it with so there's no way to check that possibility unfortunately.

As for the mobo it's definitely not the same one again because I still have the original faulty one aswell, ready to be sent back 😛. It'll just be annoying having to get another one sent out.

Just because it boots and runs does not mean that the cpu is clean.
As I said before a friend had similar symptoms and it turned out that the cpu had this same minor defect.
In testing, the defective cpu had the same symptoms in a known good motherboard and ram.
Namely the inability for dual channel operation.
Conversely, the known good cpu mounted in the suspect motherboard and ram worked perfectly.
A defective intel cpu is very rare, but it does happen.
That said, I would put it as a very low probability.

You might double check the pins in the cpu socket for damage.

 

[tom1234560]

Fair enough I suppose it's possible it could be the CPU then. I did just check the CPU socket and all the pins were absolutely fine (funnily enough the problem with the first mobo was a broken pin). So most likely it's another defective mobo, but if another replacement doesn't work I guess I should start considering that my CPU could be defective.

 

[lindbergh]

Gents, I have the exact same MB, CPU, and problem with RAM in the A channel. My RAM is GSKILL F4-3600c17d-16gtz. I plan to check the MB pins when I remove the CPU to replace the MB with a MSI Z370A-Pro. I will report back if the MSI has problems.

 

[Benster]

Gents, I have the exact same MB, CPU, and problem with RAM in the A channel. My RAM is GSKILL F4-3600c17d-16gtz. I plan to check the MB pins when I remove the CPU to replace the MB with a MSI Z370A-Pro. I will report back if the MSI has problems.

After checking the board/CPU there are no bent pins which makes me think it could very possibly be due to the CPU itself or uneven pressure caused by the cooler?

I've sent for a replacement Motherboard in the meantime so I'll update this post if I encounter the same issue, I'll also try and get the CPU tested in a rig that works to take that out of the equation.