Processors

[cengreth]

My previous computer died, so I started a new build in anticipation of Zen 3 using a Ryzen 5 2600 I picked up inexpensively. I currently have the following:

Ryzen 5 2600

Gigabyte Aorus x570 Master

Corsair Vengence RGB Pro (CMW32X4M4C3200C16) 4x8GB

When I boot into windows, it shows that I have 32GB ram installed but only 16GB usable. I played around with the ram and discovered the following:

1. Inserting each ram stick individually into slots A1 or A2 caused no problems and works as expected (single channel but all capacity as expected)

2. If I put a stick solely into slot B1 or B2, the system will not post. The LED cycles through ~4 values infinitely. I don't have them written down.

3. As long as there is a dimm in A1 or A2, the motherboard will post. Any memory placed in B1 or B2 is not used. 

4. I reinstalled everything onto a different motherboard (ASUS TUF x570 plus). The memory slots are ordered opposite the Gigabyte board. The A slots neighbor the CPU on Gigabyte, and the B slots neighbor the CPU on ASUS. Now if any dimm is placed in the B slot of the ASUS board, it will not post.

I believe this indicates that the problem is not with the motherboard or ram, and must be the CPU. Is that a reasonable assumption? Is there anything I might be able to do to rectify the problem, or would it require an RMA with AMD?

[mstfbsrn980]

Without a third generation Ryzen processor, it is difficult to infer with testing the system. The compatibility of a new generation motherboard with processors released in the past may be poor. Incompatibility causes this problem with high probability. Everything is healthy but not working properly.

I think you will solve this problem by purchasing a third generation processor as soon as possible. 

[cengreth]

Thanks for your response. Pairing an older CPU with a new motherboard is something that I did consider when I purchased the parts. I decided not to worry about it for a few reasons, chiefly because I plan on replacing the CPU with a 5000 series when they release anyways.

That said, I have a hard time believing CPU/motherboard compatibility is the problem. AMD's website lists the 2000 series (non-graphics) as compatible with x570 motherboards. My processor (and RAM) was also on the QVL supplied by Gigabyte for my motherboard model. 

[pokester]

This has been a widely reported issue with Gigabyte boards and I don't think a fix exists. For whatever reason some ram kits just don't work if all 4 slots are used. Contact Gigabyte support and see if they can tell what ram kit will definitely work. Or if you are still in your return period go with another makers board. They had this issue with the 4xx series boards as well. You would think they would have this fixed by now. I can tell you for instance MSI has no such issue. 

[cengreth]

Thanks Pokester. I don't think my issue quite matches the one you are referencing. From my experiments it seems that the slots marked B are non-functioning, regardless of the total number of dimms installed. This problem also is present across two motherboards that I tested (one manufactured by Gigabyte and one by ASUS). Interestingly the slots are ordered opposite between the two boards, but its still the B slots on both that don't work.

I think my problem generally is attributed to bent pins on the CPU or poorly installed coolers.  I have checked both of these and can't see any issues though.

[pokester]

Cool, good lucky. FYI Asus if you google also has reports of the sencondary slots not working with some memory just like Gigabyte. As you mentioned problems can trace back to lots of things. 

[mstfbsrn980]

B1-2 must be working for your system to use dual mode. With CMOS reset, use A1 first, then B1, or both after reset. Manually configuring the RAM settings might fix the problem. So I think the problem is not caused by the chipset or the processor. Maybe the problem could be the BIOS. Maybe the BIOS is unable to configure auto RAMs. This problem is unlikely to be caused by the processor. Try slower RAM speeds. Or try changing the timing settings. With tring CMOS reset.... ...

[mstfbsrn980]

Use 3000 for RAMs speed, not 3600...

[cengreth · Accepted solution]

I ended up picking up a replacement CPU, and the problem is resolved. I can now use all of the ram slots. Thanks pokester‌ and mstfbsrn980‌ for your help.

[mstfbsrn980]

I told you this from the beginning that backward compatibility will be a problem.

[pokester]

Awesome! I am so glad you got it figured out. I hope you then RMA the other cpu. It is rare for cpu's to be bad but sadly I have seen more reports like yours in these forums over the past year that reflect that it is more prevalent. 

It is one reason I like to suggest users work with the motherboard support departments as they can usually in short order pinpoint if it is them or the cpu.

Anyway I hope you have a much more trouble free computing experience. 

Good Luck and thanks so much for sharing what worked. It helps the community greatly!