RAM update

I have a pre built pc that only have a 8gb ram so how much ram should I get because I have ddr4 ram it tell what ram should I have

I have upgraded my ram in my Acer nitro 5 laptop from this...

Currently I am running the following: i7 4790k OC to 5.2Ghz NZXT Kraken x62 16 GB of RAM (cannot remember speed...) GTX 1080 Ti FE Corsair RM650x Samsung 970 Evo (currently running in 1/3 of performance due to PCIe 2.0...) Asus Z97 - PRO GAMER I am thinking of upgrading to the following...

P57NA-VM not seeing 16gb 800MHz RAM. What is the process in BIOS to install 16gb 800MHz ram from 667MHz BIOS v2.16 installed several attempt made instructions are not clear. how to upload images here? Have pics of BIOS

A couple days ago I got some new RAM for my system. I already had 2x4gb HyperX DDR4 2133, and I got 2x4gb at 2933 and installed it. Soon after I got a blue screen, I don’t know the error code, but I went into BIOS and turned the speed down of all the RAM to 2133. I then got a few more blue...

Newly built PC, when I turn it on it starts to do all the POST checks, gets past CPU just fine however after the DRAM led goes off the VGA led never comes on and the system shuts itself off. It proceeds to restart and do the same cycle endlessly. When there is no ram in the board I get the no...