Another mixing ram question

jhsu

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Sep 30, 2018
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I have a threadripper system on an Asrock Taichi x399 board that has 8 ram slots.

Originally I had 4 sticks of 8GB ddr-3000 CL15-15-15-35

Just upgraded to 4 sticks of 16GB ddr4-3000 CL16-18-18-38

I was planning on just swapping and selling the old sticks, but figured what the hell and just tried them all. To my surprise The system boots and this is what I get with cpu-z:
2019-04-05_19-01-57_cpuz-new_ram.png

I was able to get 2933MHz before with just the old ram by selecting xmp profile in the bios, but now when I try it the system will fail to boot 3 times, do some error correction and then boot normally at 2133MHz.

I tried manually setting the ram timings to 16-18-18-38. Not sure if I was doing it right or not, the same thing would happen with the boot failures 3 times then normal boot and all the settings show the same as above in cpu-z.

So my question is, should I keep all the ram at the lower speeds, or should I get rid of the older ram and stick to my set of 64GB so that I can get better speed and stability?
 
My take on this is only you know what you should be doing:

1. If you have a lot of RAM intensive work where quantity is more important than raw speed (I guess you know by now that Ryzen performance is tied to RAM speed), keep all the RAM and run the speed low
2. If you don't use all the RAM anyway, may as well sell the old RAM.
3. It appears you haven't done a lot of tweaking with the RAM yet (voltage, timings, gear down settings). May as well give it a go? Depends how much time you have though. Not sure if you've done this already, but try populating the old RAM into the same channels and the new RAM into the others. Try to experiment with this as well I guess. My guess: Old RAM in channels A and B, New RAM in channels C and D

Hope this helps
 
Some software like Cinbench fit's within CPU cache and as such doesn't benefit from faster RAM while with other software the CPU waits on data from RAM and faster RAM can increase CPU performance by around 20%
f you want to try get the RAM operating at a higher speed make sure your BIOS is up to date and follow this guide
https://www.techpowerup.com/reviews/AMD/Ryzen_Memory_Tweaking_Overclocking_Guide/

There is also some great info here

https://www.overclock.net/forum/10-...-ryzen-ddr4-24-7-memory-stability-thread.html
 
Last edited:
I'm sure that running 8 sticks of mix and match sizing is throwing it off. Probably all you're going to get is the lower speed. Maybe 2400 or 2666. If it were all the same size, you could probably run it at full speed at the looser timings.
 
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