I need help repairing my grand parent's computer!

[Jyn]

Hi, I am reaching out in hopes of some helpful answers regarding fixing my grandparent's desktop. 
Long story short, my grand parent's were experiencing some issues with their computer and I offered to repair it for them, after hooking up the computer I booted into windows with no issues, I downloaded and reinstalled a fresh version of Windows 10, afterward I removed all the components from the computer and gave the inside a deep clean and put everything together now I am experiencing issues with the RAM the two sticks that came with the computer are no longer working together I can only use one of the RAM sticks. I have provided a before & after picture of the boot screen showing my issue. (note* pressing the DEL key doesn't open the BIOS anymore)

BEFORE I REINSTALLED WINDOWS & CLEANED INSIDE THE COMPUTER.

AFTER I INSTALLED WINDOWS 10 / CLEANED THE INSIDE OF THE COMPUTER

All help is appreciated, thank you

[b0tscape]

• Reset the cmos
• Adjust any bios settings so the timing/voltage of the ram chips are default
• Change the slots where the ram is installed
• Is the ram ecc, has it got a different voltage than the one you're using
•  

[Gunman]

Try re-sitting the ram sticks and swapping the slots around.

[Jyn]

15 minutes ago, Gunman said:

Try re-sitting the ram sticks and swapping the slots around.

Thanks for the reply Gunman I have tried swapping around the RAM sticks switching the slots and it will not work, the only way it will be boot is with one RAM stick in.

20 minutes ago, b0tscape said:

• Reset the cmos
• Adjust any bios settings so the timing/voltage of the ram chips are default
• Change the slots where the ram is installed
• Is the ram ecc, has it got a different voltage than the one you're using
•  

I have reset the cmos multiple times (not sure if I'm doing it correctly but I removed the cmos battery) 

I'm unable to enter the BIOS on start up for some odd reason.

I've swapped the RAM between both slots and it refuses to boot when both are installed.

The RAM is the same RAM that came with the computer originally.

[Gunman]

@Jyn If both ram sticks work when tested in one slot, and if you swap it to the other DIMM slot and it works, then maybe try re-sitting the CPU?

EDIT: Just remembered a weird issue I had a while back. If the pc is sitting up right when you're putting the ram in try sitting it down on it's side. For some reason one slot on my old MOBA didn't like it when I had the pc sitting up right when putting the ram stick in, but when I put it on it's side and put it in, it worked fine.

[StarCraftSniper]

You have bad ram slot I'm guessing.

Buy a cheap used mother board

 

Try defaulting the bios settings before you replace though 

[Billon]

Oh, you can try to solve it by replacing the memory cards