Question Having issue using different speeds ram

[braydennv]

Mobo - Asrock b450m pro4
cpu - ryzen 5 2600
ram - (the important part in the discussion) currently using corsair vengeance lpx 2x8 3200mhz, and im trying to add corsair vengeance lpx 2x8 4000 mhz and clock it all at the 3200s speed and timings.

(Not so important: psu - evga 550 80 gold, samsung 970 evo plus 500gb, gpu - rx 6600 eagle 8 gb)

I bought the 3200 ram a while back and decided to buy another set of 2x8 just to have more ram for niche things because why not. well, i decided to buy ram that has a higher speed so when the 3200 becomes slow in the future i can just use the 4000 and buy more 4000s. anyways, when i put the 4000s in in any orientation it shows 32gb. but wont clock to 3200 and when i get it running it wont actually use all 32gb of ram, it only uses 16gb and displays 32gb and 4 slots being used. also i tried the 4000 and eventually got it to run at 3200 by its self just two slots being populated but when i got on my pc in the morning it hit me with a bsod pretty quick.

 

[punkncat]

A couple of comments here:

It is never advised to try and use mismatched kits of RAM. In particular, it is a bad idea to try this with Ryzen, and even more so the early versions. So, easy answer would be to just pony up and buy a matched kit to try.

It may be worthwhile to attempt to update the motherboard BIOS to as late a version as you can use with the 2600 and see if you can set manual timings.

A suggestion I make is to load the "slow" kit and use CPU-Z to get your timing tables for JEDEC and XMP. Take a picture or write notes. Go into BIOS and set to default, exit, and load the "fast" RAM. Hopefully the system can boot with it, and you can see what its timing tables look like. Try to see if the tables intersect somewhere, or might work through slower timings. Voltage can also be a factor.