I have been using these on my desktop happily for several months. Out of stupidity, I decided to fill up all 4 memory slots only because 2 of them were unoccupied. And then trouble came.
My system before the upgrade:
- Asus PRIME B450M-A motherboard
- Corsair DDR4 8G x2 rates at 3200mhz (CMK16GX4M2B3200C16)
- AMD Ryzen 2700
- Ubuntu 19.10 with kernel 5.4.2
Just the night before, I realize my memory were running at 2133mhz. I went to the BIOS, enabled DOCP, and got them to run at 3200mhz. I ran my usual applications and they all worked fine. I did not notice any significant performance change though.
Next day, I got myself another pack of 2x8g DIMMs. Same brand and part number. The heat sinks are in a different color, but I was assured they are the same.
After plugging them in, the system would not pass POST. The motherboard beeped and power cycled 3-4 times. BIOS finally booted and warned me about previous unsuccessful boots. Memory clock was reset to the default 2133mhz. I then tried lowering the DOCP clock to 2866mhz. The system boots, but applications were crashing. I further lower it to 2400mhz, and the system has been stable for the past 12+ hours. I suppose I can try something between 2866 and 2400mhz. But at this point I was feeling frustrated already.
I checked the CPU and chassis temperature are well below thresholds. Plenty of power from the power supply. I can only suspect the new DIMMs are unable to run at the rated clock speed – not even close. Even though they are from a reputable brand and a reputable shop.
It’s too much work to take them back. It’s a stupid upgrade. I had been rarely able to use more than 10g of memory.
Very soon, DDR4 will become obsolete. AMD is going to use DDR5 on newer Ryzen CPUs. So the next upgrade will require a new board and new DIMMs. It’s a shame we need to spend on something we don’t need.
These are what I have now:
▶ sudo dmidecode -t memory | egrep '(Size|Speed|Part)'
Size: 8192 MB
Speed: 2400 MT/s
Part Number: CMK16GX4M2B3200C16
Configured Memory Speed: 2400 MT/s
Size: 8192 MB
Speed: 2400 MT/s
Part Number: CMK16GX4M2B3200C16
Configured Memory Speed: 2400 MT/s
Size: 8192 MB
Speed: 2400 MT/s
Part Number: CMK16GX4M2B3200C16
Configured Memory Speed: 2400 MT/s
Size: 8192 MB
Speed: 2400 MT/s
Part Number: CMK16GX4M2B3200C16
Configured Memory Speed: 2400 MT/s
Update on 2021-06-01
Recently updated my motherboard BIOS to version 2409, and I gave memory overclock another try. Tried 3200/3000/2933Mhz, I couldn’t pass POST. The motherboard gave me 3 beeps and hard rebooted. Lowered to 2866MHz and I got pass POST and the OS boots. Hope it’s stable.
▶ sudo dmidecode -t memory | grep Speed | grep -v Configure
Speed: 2866 MT/s
Speed: 2866 MT/s
Speed: 2866 MT/s
Speed: 2866 MT/s
I don’t do games. I compiled the linux kernel and see if the memory speed bump gives me anything. Kernel 5.12.8 was compiled with -j12 using gcc. Before the overclock, the job took 15.51s, and now it took 14.55s. A bit faster then.
Update on 2022-03-08
System was previously not stable enough and I disabled DOCP. Today, I’ve installed a newer BIOS and enabled DOCP again. This time memory clocked at 2866MHz. So far Ubuntu boots up fine and all my application works. It is noticeably faster than without DOCP. Going any higher results in 3 beeps and BIOS F1 prompt.
▶ sudo dmidecode -s bios-version 3211 ▶ sudo dmidecode -t memory | grep Speed | grep -v Configure Speed: 2866 MT/s Speed: 2866 MT/s Speed: 2866 MT/s Speed: 2866 MT/s
Update on 2022-11-16
Today I upgraded my CPU to Ryzen 7 5700x. It’s a relatively affordable upgrade and I get to keep my AM4 board and DDR4 RAM. Interestingly, the spec on the new CPU stated clearly, that for 4x1R memory configuration, the max memory speed is 2933MHz and that what they have been running in the last 30min. So far they’re working well. I suspect the previous instability issue was due to restrictions on the old Ryzen. On AMD’s site, 2700 supports up to 2933MHz but probably applicable to 2x1R?
Anyway, the CPU upgrade is amazing. AES encryption, 7z compression, and x265 encoding improved by 19% 68% 95% respectively. Libvirt VM feels 2 times faster, if not more. Compiling linux kernel 6.0.x went down from 19 minutes to 15.
That’s impressive leap considering the new CPU is just HK$1530. Fantastic job AMD!
