[SOLVED] Upgrading/changing RAM and question about compatability

[Arnikas]

Hello.

I currently am playing CPU heavy games with not the best performance I can get (Post Scriptum about 40-70FPS) and I want to upgrade my RAM to help performance. As I currently have a single channel 1x16GB 2666MHz RAM (check RIG down below), I want to upgrade my RAM to Corsair Vengeance PRO RGB 2x8GB 3000MHz CL15 sticks to get dual-channel performance.
Does that mean that I can use my old 2666MHz one afterwards or it will cause problems (adding Corsair Vengeance PRO RGB 1x16GB 2666Mhz CL16 stick to Corsair Vengeance PRO RGB 2x8GB 3000MHz CL15 sticks aka 3 sticks intogether). I do know that it would run on the 2666MHz then, but I would like to keep it as a backup if eventually in the future RIG needs more than 16GB of RAM to run.
Can I run those sticks together is my question?

My current rig
GPU: Gigabyte Nvidia Geforce GTX 1080TI 11GB
CPU: i5-9600k OC to 4.8GHz
Current RAM: Corsair Vengeance PRO RGB 1x16GB 2666Mhz CL16 stick
Resolution + monitor: playing on 1080p ASUS PG248Q 144Hz with G-Sync enabled
SSD: Kingston A400 500GB SSD, I got 1x extra SSD + 1TB HDD
Drivers are updated.
Motherboard: Gigabyte Z390 UD

 

[thx1138v2]

When mixing RAM it's always a crap shoot if they will run together. The manual for that motherboard doesn't show any setup for 3 modules. So the answer to your question is maybe but unlikely.

 

[prateek320i]

Mixing a RAM module of higher frequency with a lower frequency one is not a good idea. The system will underclock the faster stick to match the slower one. By system, I mean the BIOS on the motherboard itself, not the Operating System you run on top.
You'll get 16+(8x2) gigs of volatile memory, all @ 2666 MHz. You may be greeted with the Blue Screen of Death if your DIMMs just don’t like each other.

 

[Arnikas]

May blue screen of death corrupt my PC or for an example it does it and I understand it cannot match and I take off the extra RAM it runs fine?

 

[prateek320i]

Two things to keep in mind.

1. BSOD doesn't corrupt hardware components. But sometimes OS may be compromised (less likely). You may experience loss of unsaved data. It can ruin your day when it comes to gaming.
2. You need to take off either of the RAM Stick, choose b/w 2666 or 3000.

My opinion- 2666 MHz is also a good option, either add DIMM of 2666 MHz OR discard and sell this module, buy a whole new set of higher speed.
This graph will help you understand more about Latency vs Speed

You see, there is a difference of nearly 2 nanoseconds jumping from 2400 MHz to 3200 MHz (absolutely negligible, milliseconds would have an impact). So, I’d prefer sticking to 2666 MHz, as I don’t do batch pictures processing or movie editing, I’m purely into gaming.