[SOLVED] PC won't boot with new RAM kit

Jun 14, 2021
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Mobo: Gigabyte GA-78LMT-S2 (two ram slots will support up to 16 GB of Ram at 1333mhz)

Purchased: G.Skill Ripjaws X Series 16GB (2x8) DDR3 SDRAM 1600mhz to replace my old 2x4GB Ram

Here's my issue: each of the new 8GB sticks will work with one of the old 4GB sticks, giving me 12GB of Ram, at least according to my system info. However, my pc won't boot up when both of the 8GB sticks are plugged in at the same time. It will only boot if one of the old 4GB sticks is in one of the two slots.

I've scoured the internet but I can't find an analogous issue. Any help is greatly appreciated!
 
Solution
Mobo: Gigabyte GA-78LMT-S2 (two ram slots will support up to 16 GB of Ram at 1333mhz)

Purchased: G.Skill Ripjaws X Series 16GB (2x8) DDR3 SDRAM 1600mhz to replace my old 2x4GB Ram

Here's my issue: each of the new 8GB sticks will work with one of the old 4GB sticks, giving me 12GB of Ram, at least according to my system info. However, my pc won't boot up when both of the 8GB sticks are plugged in at the same time. It will only boot if one of the old 4GB sticks is in one of the two slots.

I've scoured the internet but I can't find an analogous issue. Any help is greatly appreciated!

On the surface, it sounds like when both of the 1600mhz sticks are in, its being defaulted to a higher speed than 1333mhz which would be higher...
Mobo: Gigabyte GA-78LMT-S2 (two ram slots will support up to 16 GB of Ram at 1333mhz)

Purchased: G.Skill Ripjaws X Series 16GB (2x8) DDR3 SDRAM 1600mhz to replace my old 2x4GB Ram

Here's my issue: each of the new 8GB sticks will work with one of the old 4GB sticks, giving me 12GB of Ram, at least according to my system info. However, my pc won't boot up when both of the 8GB sticks are plugged in at the same time. It will only boot if one of the old 4GB sticks is in one of the two slots.

I've scoured the internet but I can't find an analogous issue. Any help is greatly appreciated!

On the surface, it sounds like when both of the 1600mhz sticks are in, its being defaulted to a higher speed than 1333mhz which would be higher than the mobo allows and not allowing the pc to boot. And when you use the older stick (maybe it has a lower speed?) its defaulting the speed to the slower speed within spec of the mobo allowing the pc to boot.

Put ram in that works, try going into the bios and manually setting the ram speed to 1333mhz, then put the 2 8gb chips in and see if it works.

On a side note, why buy 1600mhz ram if the mobo only supports up to 1333mhz?
 
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Solution
Jun 14, 2021
2
0
10
I manually changed the speed to 1333mhz and that fixed it! It was on auto before, although it was still set at 1333. I wouldn't think that would make a difference but it did. Thank you for your help, Jason.

To answer your question: I didn't know there was a difference in Ram speed tbh until I started researching why it wasn't working.

Another question: should I change the speed to 1600? Since my mobo only supports 1333 is there any benefit?
 
I manually changed the speed to 1333mhz and that fixed it! It was on auto before, although it was still set at 1333. I wouldn't think that would make a difference but it did. Thank you for your help, Jason.

nice man! I figured it was that.

Another question: should I change the speed to 1600? Since my mobo only supports 1333 is there any benefit?

No. If you go over 1333mhz, the pc will not boot. When it says it only supports up to 1333, its saying that is the max. You cannot go above that or the pc will not work. What was happening is exactly what I thought was happening. The new ram was defaulting above 1333 an not allowing the pc to boot since the max it supports is 1333. Its not like overclocking, going over the max limit as Ive said will make the pc not work.

Feel free to choose a best answer to mark the thread as solved and so others who have this same issue can find a possible fix :)