[SOLVED] Maybe my motherboard doesn't support higher speed RAM?

Jan 16, 2022
Long-time lurker, first-time poster. Thanks for all the help and advice you guys have offered me over the years.

I have a matched set (2x) of A-DATA 8GB 2400 RAM installed. Works fine.

I went to replace them with Corsair 8GB 3600 RAM
(2 matched sets (4x8GB)
(The serial numbers on them are ...110-111 and ...133-134)

The motherboard (ASUS X99-A/USB 3.1) gave an angry red light to both RAM banks (the motherboard has 2 banks with 4 slots each) and could not turn on. Memory Okay (by pressing the button) could not find a usable configuration. The problem remained with one set (dual set-up and not) and with one stick.

When the A-DATA memory was added back in (dual then single), BIOS and Windows 10 would only recognize one stick (in the C1 slot for whatever reason). CPU-ID saw them all and said that there was 48 GB installed.

My only guess is that the motherboard doesn't support 3600 speeds. I can't find any documentation one way or the other. Setting the speed and voltage in BIOS to the Corsair memory (with the A-DATA memory uninstalled) doesn't get me anywhere (and requires me to reinstall the A-DATA stuff and use Memory Okay).
Jan 16, 2022
Here are the PC components. It was built in Jan 2016, graphics, water cooler, and hard drives have been replaced since then.

Motherboard: Asus X99-A/USB 3.1
Processor: Intel i7 5820k @ 3.3 GHz
Cooling: Cosair water cooler (I don't know the model number); 2 case fans
Graphics: Nvidia GeForce RTX 3070 (8GB) (GA 104-302)
Memory: As above
Hard drives: 2 500GB SSD; 1 1TB SATA; 1 1TB SSD (PCIe)
Disks: Modisk BluRay read/write drive