Question Bought additional 2x8 RAM, PC won't start - restarts after 10 sec, any help please? (provided specs)

BiscuitBar

Commendable
Feb 14, 2019
1
0
1,510
Hello! My PC is:
Motherboard: X99-UD4-CF
RAM: CMK8GX4M1A2400C14
CPU: i7 5820K
GPU: R9 290 X

Despite this being quite an old build, it was doing just fine until recently - lately under certain conditions 16GB ram was just not enough to run certain set of Apps.
So I bought two more 8GB cards - CMK8GX4M1A2400C16. I kinda expected that there would be no conflict since models are so similar and, supposedly, my mother supports 4x channel. I guess I made a mistake somewhere?
After installing two additional memory cards into 3rd and 4th slots, PC won't boot up properly: there is no image on monitor, despite PC seemingly working propetly, and after ~10 seconds it restarts (stops for a second and boots up again), this happens indefinitely.
Can anyone give me some advice?
 

Aeacus

Titan
Ambassador
Do not mix RAMs, it's a bad idea. Also, timing is different between your old RAM and your new RAM. That alone can be reason why your PC won't POST when new RAM is in the PC.

To minimize the RAM compatibility issue, get the exact same make, model and part number RAM you already have. And even when you've done that, chances of old and new RAM working together would be 50:50.

There's a reason why RAMs are sold in a set, e.g 2x 8GB or 4x 8GB, since with RAM sets, the RAM manufacturer has tested, confirmed and guaranteed that all RAM sticks in a set will work together without issues.

Further reading, link: https://forums.tomshardware.com/faq...ocp-memory-profiles-work-in-progress.3398926/
 

shknawe

Respectable
Oct 22, 2016
1,287
47
2,490
Remove the new ram, go into bios and set the timings to match the new ram. Then try installing all the ram and see if it fires up. If not you will have to sell one or the other and buy exact matching model ram with exact timings.
 
Memory is guaranteed in the form sold. Memory modules sold as Single modules have no guarantee to be compatible in any configuration other than as a Single module.

Use of exact match, same thing, identical may increase chances of memory working together over the use of random modules, but have no guarantee to be compatible together.
 

Sxino

Honorable
Apr 3, 2015
62
3
10,645
Everyone is suggesting to return your memories, but I think you came here to find a solution to use them together.

I have also mixed different memories in my old system so this is what I have done:

  1. Take out old ram
  2. Install new ram in 1st and 3rd slot
  3. If it cannot boot, try installing only one in the 1st slot. If cannot boot it definitely not working in your system.
  4. If it boots, turn off your PC and install the old ram in the other 2nd and 4th slots.
  5. Turn PC on
  6. If cannot boot, you need to work with the new ones or old ones only.
  7. If it boots, go to BIOS immediately and go to the memory tab and change the timing of the ram to 16-16-16-39.
  8. Save changes and reboot.