The motherboard is an ROG Rampage III Black Edition motherboard. To make a long story short, I've been using it for years and it's been great. Recently, though, I've been upgrading the system and have run into an interesting issue concerning memory. I followed the manual and got six sticks of identical new memory with the desire to upgrade from 12 GB to 24 GB--seeing some stutter sometimes while streaming Netflix video at 4K and wondering about the cause. The memory purchased is listed in the QVL list, and I thought it was reasonably priced, and the brand seemed fine, etc etc. However, I did not poke around too much for information about set up, various kits available, etc., etc., and did not know what to expect once I'd installed it except for a possible end to the stutter and perhaps other minor improvements here or there--which I know may be unreasonable given 12 GB of memory is more than enough for most users most of the time. I've boosted memory in laptops with next to no effort, though, and was astonished seeing huge improvements. I doubted that would be the case here, but the process was a snap. In summary, I was mainly shooting for more memory because the system is old, and have been thinking it may be hard to get new memory down the road and it might be good to have extra working memory on hand should there be problems. And there might also be need for more memory down the road for said game, or whatever... Anyhow, I went ahead and installed it.

Well, here is the issue. After installing the memory, Windows 10 (if you right click the start menu and go there) shows only 16GB. CPU-Z shows everything as expected--24 GB installed, correct timing, voltages, etc. So, what is up here?

Also, on an aside. On startup the system now starts and stops twice before booting. What is that about?

Edit: Later in the day now, after shutting the system down, it now starts and stops a few times before booting--and just before powering down stops after error code 69 appears (then "FF") (69 = System Agent DXE initialization is started). After that it runs well--but remains unable to see all of the memory installed. Also, HWMonitor is showing the systems and not only just seeing 16 gb of the 24 gb installed, but it also calculating % of memory used based on 16 gb vs the 24 gb installed.

Also, I've been looking around and doing searches and reading forums and posts related to the x58 chipset in a lot of motherboards, and have found such problems are widespread. Viable solutions, though, seem few and far between. Also, even people with "supported" 24 gb ram kits are having these problem.

Anyone with any related experience, knowledge or fix for these issues--thanks in advance.