Question 16+8

Sep 6, 2020
6
1
15
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My ASUS Prime 250M-A, Core i5-7400, initially had a single Kingston 8GB module (9905702-017.A00G) channel 1A. I added a Corsair 8Gb module (CMK8GX4M1A2400C16) in channel 1B. All was good.
When I added two Corsair 4GB modules (CMK8GX4M2A2400C16) in 2A & 2B my desktop would not boot. I tried the 2 new 4GB modules alone in 1A & 1B and it boots fine.
What do I need to correct?
 
The issue here is your mixing ram. When you upgrade your RAM you should always buy the RAM in a RAM KIT. RAM that comes together and tested to work together.

New RAM could require a BIOS update to be compatible with the board.

If you have the latest BIOS update and the RAM is not working together there is nothing you can really do. Keep the 2 8GB and remove the 2 4GB. Just buy a 2x16GB RAM KIT if you want to upgrade and remove all the old RAM.
 
Reactions: King_V
Sep 6, 2020
6
1
15
0
The issue here is your mixing ram. When you upgrade your RAM you should always buy the RAM in a RAM KIT. RAM that comes together and tested to work together.

New RAM could require a BIOS update to be compatible with the board.

If you have the latest BIOS update and the RAM is not working together there is nothing you can really do. Keep the 2 8GB and remove the 2 4GB. Just buy a 2x16GB RAM KIT if you want to upgrade and remove all the old RAM.
Going from 8 to 16 mixed the ram and it was fine. One of each. Now I'm added 2 of the same brand as CH 1B and it doesn't work. I find that odd.
 
Going from 8 to 16 mixed the ram and it was fine. One of each. Now I'm added 2 of the same brand as CH 1B and it doesn't work. I find that odd.
Same brand does not mean they will work together. When you buy a RAM KIT the ram inside were made in the same batch and have the same cas latency deep down. The moment you buy same brand and model later it's not the case anymore. Yes your 8 to 16 could have worked but now you have 3 different kind of ram not from the same production batch.

It's not odd. It really is how RAM can be finicky sometimes when you don't buy ram kits. :)
 
Reactions: alceryes

alceryes

Distinguished
What @Nemesia said is spot on.
Your system may be booting with 2x4 and 2x8 but it's probably running in single channel mode with very loose timings. Unless you are constantly using more than 16GBs, running unmatched pairs will just slow your system down. I also wouldn't trust it's stable without passing Memtest86 multiple times.
Load up CPU-Z and check the memory tab to see if you are running in dual channel and at what timings.
 

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