Problems adding RAM to Optiplex 990 Bios Revision A23

Two common issues we see with memory on this forum.  (1) mixing brands/types of memory usually results in problems - only have one brand/type (2) The Kingston Value RAM is the most problematic memory type we see on here.  Most of the users that report problems with the KVR RAM never resolve their problems.  If the KVR works consider yourself lucky.

so the issue is 32GB is not registered by bios and Windows on restart, but 24GB is. correct?  Users have often found out they can exceed Dell spec limit of max 4 GB per slot. Are you putting the 32 GB in dual channel, i.e., matched ram in slot 1/3 and 2/4?  when in dual channel, it should look like ABAB for the DIMM slots 1-4, AA and BB being matched ram sticks.  What is speed of old and new ram respectively?

Thank you for your response.

Can you recommend a memory brand or attach a link of a RAM model that should be ok?

Optiplex 990 Tech Guide 

From the Tech Guide:  NOTE: Memory modules should be installed in pairs of matched memory size, speed, and technology. If the memory modules are not installed in matched pairs, the computer will continue to operate, but with a slight reduction in performance. The entire 16GB memory range is available to 64-bit operating systems.

So 16GB is the listed max, but I did find a couple of 32GB references.  Screengrabs will be below.

Something fireberd has mentioned in other posts is it's not just some Dell's that don't take mixed brand RAM.  His home built Asus won't take it either, but will take either brand.  Kind of like what you tested already.

Yet, we might hear from donm4599x.  He was able to mix his RAM in his 790 MT.  But may be certain brands don't work together?

Crucial RAM often comes recommended by a couple of our Rockstars, including fireberd.  It has a lifetime warranty and is guaranteed to work in Dell's.  If you want to save a little $ on an older machine, A-Tech RAM also has a lifetime warranty.  I used it in my previous 755.

While I've seen KVR RAM problems myself in this forum, I did find that KVR worked (for a total 32 GB) in the same thread I screengrabbed from.  It appears user may have used Kingston HyperX and KVR in the same machine.

Well @Michaelgin, options were presented.  Up to you what you want to try.  I think redxps630's options are worth a try before returning any RAM.

Screengrabs will show once approved by a moderator:

@Michaelgin 

The only thing I would add to all the good advice you already received is this:

Use a program like memtest86 or memtest86+, booted from a usb flash drive, and test your memory modules, both new and old, in whatever configurations it will work in. Be sure to get around to testing each of the modules at least one or two passes.

It's possible that one or more addresses on one of the sticks are flaky, maybe even occurring randomly.

Some folks don't believe in testing memory. But over the years, it's helped me find several bad memory modules that were difficult to pinpoint.

It can also help give you the evidence you need to warranty or return a bad module, especially if the seller doesn't believe you.

Hi @donm4599x,

As @Michaelgin tested, old RAM and new RAM work by themselves.  Would memtest86 still help?

Testing very well may not help. But there is a chance it might provide a clue, and it costs nothing, so if it were me, I would test before giving up.