[SOLVED] BIOS only recognizes half of the memory

[mbz]

I usually don't have issues with resolving anything PC related but this one has me completely stumped.

In 2011 I built my first PC and have upgraded it over the years. As far as memory goes, I installed another 16GB and for quite a while had 24GB of memory with no issues on Windows 7 Ultimate 64 bit.

However, somewhere in the last few months I've had something happen where BIOS is only recognizing half of my memory, although it does recognize all 4 slots. The upgrades I've done recently is upgrade to Win10 Pro 64 bit, install a new 8GB GPU, and install a new wireless card.

Specs:
Windows 10 Pro 64 bit
MB: H67MA-USB3-B3
CPU: Intel Core i5 2500

I realize the memory is different but I've tried extensive troubleshooting with just 1 type in every arrangement possible and still always get only half the memory recognized, although again all of the used slots register memory.

Additionally I have:

• Updated BIOS as well as install older versions, even back to my original version
• Made sure the memory limit box in Win10 was unchecked
• Reset CMOS both in BIOS and pulling/replacing the battery
• Reseated the CPU and checked for bent pins
• Removed the GPU
• Removed the new wireless card
• Run memtest86. I did get 1 error with memtest86 (test 9) but in the course of figuring out which stick caused the error I could not replicate it, even when using the same setup I used when first encountering the error.

My thought at this point is that maybe it's the motherboard but aside from this issue I have no other reason to believe that. I'm really at a loss and am hoping for some ideas for things I've haven't tried. I know it's an older PC but before I Frankenstein it with new parts I want to give it an honest attempt of fixing this issue since the PC runs with no issues aside from not recognizing all of my memory.

 

[herrwizo]

As you are already aware, you have mixed RAMs. In some cases this works, in others, well... a small change in system config and all hells breaks loose. This is not severe in your case, as simply half RAM is left unrecognized, but still...

Nevertheless, getting even a single error in memtest indicates a possibility of failing memory module or slot.

The best way to test is with a brand new dual channel kit consisting of 4x4GB modules.

 

[mbz]

As you are already aware, you have mixed RAMs. In some cases this works, in others, well... a small change in system config and all hells breaks loose. This is not severe in your case, as simply half RAM is left unrecognized, but still...

Nevertheless, getting even a single error in memtest indicates a possibility of failing memory module or slot.

The best way to test is with a brand new dual channel kit consisting of 4x4GB modules.

I tested 16GB with the 2 2x4GB modules in different configurations. Would that not be sufficient to rule out mismatching memory being the cause?

 

[mbz]

So, I sort of resolved this issue - but in truth there was none.

Since it had been 10 years since I built this system I guess I forgot some of the specs I had set up. When I pulled the RAM modules and saw the model numbers with "8G" and "4G" on each stick I was caught up thinking the two sticks with "8G" and the two with "4G" mean that was how much had. When I went back to where I had purchased the original ram and the upgrade ram I suddenly clicked that 8G and 4G was for the total set and was not specific to the individual stick.

To be sure I ordered 32GB in 4x8GB and am now showing 32GB total. Such a simple thing to miss but I'm relived it wasn't a huge issue.

At least I took the time to reapply thermal paste for my CPU!