Cannot access all memory after ramm replacment.

User has a Precision 5510. Warranty expired in August. I'm her IT guy.

Her laptop was crashing due to a driver issue. I fixed that. Its unrelated to the story other than this is what made me look at her laptop to begin with. While testing everything out before returning it I noticed that even though her laptop has 16GB ram Windows only uses 6GB. Control Panel -> System shows "16GB (6.18GB Usable)"

I went into the hardware diagnostics and it immediately failed the ram in Dimm slot A. Error code is 2000-0122, so bad Ram. I opened the laptop and replaced both dimms with brand new dimms. Diagnostic still fails dimm A. But it does not look like its actually testing it. It fails it seems by default without attempting the test. In fact, when you first load the ePSA the error comes up before the ePSA starts its tests. The verbiage with the error is "Memory errors detected. Limit exceeded. Additional errors will not be repaired."

My understanding is that when memory errors are detected the firmware tries to "repair" the bad memory. In practice it does this by reserving that region of memory so that the operating system cannot use it. In theory I should be able to replace the ram and then the reservation should clear. But that is not what is happening.

I have actually seen this issue twice before where a dimm is bad, the firmware reserves the memory that's bad so that the OS cannot use it, and even after replacing the ram, those regions of memory stay permanently reserved. In both cases support replaced the motherboard under warranty and the problem was resolved. Since this laptop is out of warranty that's not really an option.

I am looking for a way to "un-reserve" the memory so that I can access the full 16GB. BTW I have already updated the firmware to the newest version. Her laptop otherwise is stable and is working fine, and I could just give it back to the user and she would likely never notice. But I would prefer to fix the problem and let her system have access to the full 16GB if I can.