Issues overclocking RAM after adding more

[SRRAE]

Hi,

 

Basic story is, when I upgraded from an ageing i5 2500K to a Ryzen 2600 I couldn't afford 16GB of RAM straight away so went for 8GB with the aim of increasing it in a few months. I got Corsair Dual Channel Vengence CMK8GX4M2B3200C16.  Overclocking those I was about to get up to 3400Mhz stable using basic motherboard settings and even 3600Mhz long enough to do a few benchmarks.

 

A few weeks ago I was able to increase the memory. I bought the new memory from Amazon as they were selling 16GB kits for only a little more than the 8GB kits.   I made sure to get the same speed etc.  I got Corsair Vengence CMK8GX4M2B3200C16.  In theory the same as my first pair just larger.

 

However now with all modules in they are not able to be overclocked at all.  I thought it should be possible as the spec of the 2 pairs should be near identical. Even a modest overclock using the XMP settings causes games to freeze and crash within 10 mins of the game starting. 

 

My question is, the issue being caused because of the size difference in the memory modules? 
Is it likely that the 2nd lot of RAM is faulty?

Should I try to manually set the memory timings to get it stable overclocked?
Should I just remove the two 4GB modules and run with 16GB instead of 24GB?

Thanks for your help

 

 

[TrigrH]

10 minutes ago, SRRAE said:

Should I just remove the two 4GB modules and run with 16GB instead of 24GB?

Yes, sell the old ram or use it in another system, ryzen hates 4 sticks and thats whats holding you back.

[nick name]

Any RAM configuration over 16GB will put a larger strain on your IMC and you've not given enough detail for us to help diagnose.  I would say sell the old kit unless you need extra RAM.  

 

And then when you're ready to overclock I would recommend using the Ryzen DRAM Calculator:

 

https://www.overclock.net/forum/13-amd-general/1640919-dram-calculator-ryzena-1-4-0-1-overclocking-dram-am4-307.html

[porina]

By not overclock, is it running at ram rated 3200? If so, you can leave it at that to keep your maximum capacity. If you have to drop speed below 3200 to get 24GB running, maybe drop to 16GB if that is able to run 3200.

 

It is normal for the extra modules (not necessarily the quantity) to reduce speed potential. Easiest to drive is single rank per channel. By adding a 2nd module you're at least adding another rank, possible 2, depending on the 8GB modules. More rank = harder to clock, but it can give a slight bandwidth boost at the cost of a bit of latency. Very minor stuff, but benchable. On Intel systems I found the extra rank be worth about the same as a speed grade for bandwidth sensitive operations, but I don't know how that affects Ryzen.

[SRRAE]

Last night I dropped the RAM speed to 2933 (I think it was) it it was still crashing.  Again after playing a game for 10-15 mins it crashed.  I cant remember the exact exe which crashed, but the error said *Unable to write to memory"

 

I've removed the two 4GB sticks.  Keeping just the two 8GB in and I managed to run them at 3400Mhz and benchmark cinebench half a dozen times without issue, but games again crash.

I dropped it to 3200Mhz and left it benchmarking Haven all night (about 7 hours) and there seemed to be no issues.  I'll test again tonight playing an actual game.

[SRRAE]

Set the memory to 3400Mhz, CPU and Memory stress tested for 2 hours.  GPU benchtest ran all night and been playing games for about 3 hours and not a single issue.

Thanks for your help.
I have some RAM to put on Ebay now