If RAM has been switched from slot 1 and 3 to 2 and 4 it means that slots 1 and 3 are broken.
This can indicate oxidized pathways of the mobos, firmware error, contact with socket issues or IMC on CPU is FUBAR.
Next step (easiest) would be to check if there is a BIOS update available and update it then reset to default values and re-set everything.
You do that by going here:
Download Page.
Click Windows 10 64-bit and go to the BIOS option and download the 2203 version, after this unzip the file to a small 1 or 2 GB USB stick (remember the filename!) and go into the BIOS of your PC, you go to the "tool" tab and select "EZFlash 2" I believe it's called.
From there you find the USB where you unzipped the file to, and direct it towards that file and press enter on it, the follow-up should be self explanatory.
After it's fully updated you go into the BIOS and select "Load default values" and "Save and exit" after.
Following that (if it failed) you COULD try to re-socket the CPU and inspecting if there are bent pins inside the socket itself or if the CPU contact pads have any weird marks, clean it with the same IsoPropyl Alcohol (CPU ONLY!! NOT THE SOCKET!!) and place it back in again.
If there are no marks and neither of the above works it means 100% that either motherboard RAM pathways are oxidized (bigger chance) or the IMC on the CPU is busted (rare) ... the first would allow a "simple" mobo exchange to get full working order back of the RAM and the 2nd would require a CPU replacement to get it to work.
However IMCs tend to fluctuate and I can see your RAM speed is far higher than your BIOS has set it to so let's try the following as it'll increase voltages to the CPU and IMC and possibly kick the IMC to work with more juice.
I see you have an ASUS P8Z77-M motherboard, press F7 in the first BIOS screen to go to advanced mode.
Here you go to the AI Tweaker tab (IIRC) and you should have a option called "Ai Overclock Tuner" or similar, it should be the first option on that page.
Press enter on that and select X.M.P. - A new button below should appear with contents stating Profile #1 or Profile #2.
Try keeping it on "Profile #1" and then press F10 for save and exit setup.
Shut down the PC entire after this, wait 10 seconds after it's completely powered off and start it up again and go into the BIOS and show me a picture of the first screenshot again.