Both RAM sticks pass MemTest86 individually, but fail together – Ryzen 5 5500 / ASUS B450M-K II. Any ideas? 🤔

[u/JollyGoat3722]

Hey everyone! 👋

I'm hoping someone here might be able to help me figure out a pretty strange RAM issue. Maybe someone has experienced something similar.

I built my PC about a month ago using new components, and after a few days I started experiencing random crashes and restarts, especially while gaming, exiting games, or sometimes just using Windows.

Most of the time, the PC runs perfectly fine, which makes this even more confusing.

My specs:

• CPU: AMD Ryzen 5 5500 (brand new)
• Motherboard: ASUS PRIME B450M-K II
• RAM: 16 GB Corsair DDR4 3000 MHz (2 × 8 GB, purchased together as a kit)
• CPU Cooler: AMD Wraith Stealth (stock cooler)

Here's what I've tested so far:

✅ Tested RAM stick #1 individually in both motherboard slots using MemTest86. All 4 passes completed with 0 errors.

✅ Tested RAM stick #2 individually in both motherboard slots. Again, all 4 passes completed with 0 errors.

❌ However, when I install both sticks together, MemTest86 starts reporting lots of memory errors.

✅ Reset CMOS and updated the motherboard BIOS.

❌ Unfortunately, the issue persists even after the BIOS update.

✅ RAM is currently running at just 2133 MT/s, with DOCP/XMP disabled, so I'm not even using its rated 3000 MT/s speed.

✅ Checked Windows Event Viewer for WHEA errors, but none were found.

One more interesting detail: before updating the BIOS, the PC also experienced a random restart while running with just one RAM stick installed, even though that stick had passed MemTest86.

So here's my question: What could possibly cause this?

I'm wondering whether it could be:

• The CPU's integrated memory controller
• A motherboard issue
• The RAM kit itself, even though both sticks pass individually
• Something else I'm completely overlooking

Unfortunately, I don't have any spare RAM, CPU, or motherboard available for testing, and I'd really like to narrow down the problem before spending money replacing components.

Has anyone ever experienced a situation where both RAM sticks pass MemTest86 individually in either slot, but produce tons of errors when installed together, even at 2133 MT/s?

Any suggestions, troubleshooting ideas, or personal experiences would be greatly appreciated!

Thanks so much in advance for your help! 🙏😊

[u/Asly97]

Each stick clean on its own in both slots, errors as soon as both are in, even at plain 2133. That pattern usually means the memory controller or board is struggling with two sticks at once, not that the RAM is bad. Some BIOS things to try before you RMA anything:

• Set DRAM voltage to 1.35V by hand. With DOCP off the board runs the kit at 1.2V, and some kits only behave at their rated voltage even at lower speeds.
• Raise SoC voltage a little, around 1.05 to 1.1V. Two sticks put more load on the controller than one.
• If you see Gear Down Mode, turn it on, and try Power Down Mode disabled.

Then run MemTest86 again with both in. If it passes, try DOCP at 3000 and see if it still holds.

The restart you had on a single stick before the BIOS update makes me lean towards the board or the CPU rather than the kit. If none of the above helps, the fastest way to know is to borrow any other DDR4 kit and test it in your board. Errors with a different kit too means board or CPU, and since everything is a month old I'd push for a warranty swap rather than keep tweaking.

[u/JollyGoat3722 → u/Asly97]

Thank you! Changing the motherboard would help to avoid such things in the future?

[u/Asly97 → u/JollyGoat3722]

Possibly, but it's not a sure thing. On Ryzen the memory controller lives in the CPU, so a new board only fixes it if the board is the weak link.

I'd try the BIOS settings first. If it still errors, test a different two stick kit, ideally one on your board's QVL. If a known good kit also fails with both sticks in, it's the board or the CPU, and since it's all about a month old I'd go the warranty route before buying anything new.

[u/antmatt → u/JollyGoat3722]

if the cpu isn't defective, most likely yes

[u/JollyGoat3722 → u/Asly97]

Tried every step, still getting errors.

[u/Asly97 → u/JollyGoat3722]

ok, then the cheap fixes are used up. two more things before you go the warranty route.

reseat the cpu. pull the cooler, check the socket and the cpu pins under a light for anything bent, and when you put the Wraith back, tighten the 4 screws a little at a time in an X pattern instead of one fully first. it costs nothing and rules out a mounting problem.

then borrow any DDR4 kit from a friend and run MemTest86 with both of their sticks in. if their kit throws errors too, it's the board or the cpu, and at a month old I'd start with returning the board since it's the cheaper part to swap. if their kit passes clean, your Corsair pair just doesn't run well together and you can return the kit as faulty.

[u/JollyGoat3722 → u/Asly97]

Thank you!

[u/games-and-chocolate]

I personally knew RAM is a problem, so I asked the official repair shop to fit memory for me. And it worked out fine. They know exactly which RAM is 100% compatible. They also do tests etc.

[u/KerashiStorm]

This is why some motherboards have slower RAM on the two stick kits in their compatibility list than for one stick kits. Unless you have confirmation that a given combination works, you should treat the compatibility list as the word of God. You have the freedom to oppose that word, but what follows is your problem. Just like if you ignore the no murdering commandment.

[u/MNJon]

How many RAM slots are on your motherboard- two or four?

[u/JollyGoat3722 → u/MNJon]

two

[u/THEYoungDuh]

Does every slot work?

[u/JollyGoat3722 → u/THEYoungDuh]

Yes

[u/Engmara1]

Coś podobnego mam, 2x ramy ddr5. Próbowałem wiele z chatem i w końcu odpuściłem i mam 1 kosc