Question PC Apparently Not Recognizing 8GB Ram Sticks

[LTL428]

I was tired of games lagging on 8gb of ram, So I decided to get 2 8gb sticks (to replace my 4 2gb sticks). They arrived and I installed them, making sure to put them both in the same channel so they would work properly, and nothing. I got an error beep (which led up to me buying a new motherboard because I didn't know the ram was the issue.) the first time but I eventually figured out the ram was the problem, so I switched back to my 4 2gb sticks. I bought a single 8 gb stick after, because I thought the ram was just dead. I tried THAT stick, and got the same problem. They were not from the same seller, by the way.

Specs:
PC: Dell Optiplex 7020 MT
Graphics card: Nvidia quadro K5000 (Soon upgrading to a gtx 780 TI)
CPU: i7-4790s
The "faulty" RAM: 3x 8gb DDR3 1333 MHz (The last one might have been a 1600MHz)

Please help me.

 

[Lutfij]

The "faulty" RAM: 3x 8gb DDR3 1333 MHz (The last one might have been a 1600MHz)
Might want to pass on the makes and model of all the sticks of ram used, if you're mixing and matching them.

which led up to me buying a new motherboard
Did you replace the board with an aftermarket unit?

As for your motherboard on your prebuilt, what BIOS version are you on at this moment of time?

 

[LTL428]

The 2x8gb sticks I bought were both for dell precision, and then the standalone 8gb stick was an HP branded stick. The first time I tried using the 8gb stick alone so its not a problem of mixing different rams.

Here is the bios version I'm running: