Can I mix 1.5v and 1.35v RAM?

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TheeAnonymousOne

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Mar 25, 2016
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So, I have an ASUS ROG G750JM, and I'm just not sure. There are tutorial videos upgrading this computer's RAM from 1.35v to 1.5v, and there are forums saying 1.35v is required on this system.

I accidentally ordered a 1.5v stick, but it's almost identical to the RAM currently in my computer except for voltage and size.
Currently installed:
2x Kingston 1.35v 4GB RAM SODIMM 1600Mhz

What I bought:
1x Kingston 1.5v 8GB RAM SODIMM 1600Mhz

There is nothing in the BIOS for RAM settings, only states how much is in there.

Note: My computer has 4 slots, 2 are taken by the 2x4GB 1.35v sticks
So, to cut straight to the point: I installed the 1.5v RAM in the 1st slot, and turned on my computer. My computer turned on, but the screen did not. The fans went FULL BLAST.
I took the 1.5v stick out, and put it into the last remaining slot. It booted fine, but a little slower than usual. I checked CPU-Z, the two 1.35v sticks were running at 1.35v, the 1.5 at 1.5v. My computer recognized all 16GB. I haven't tried using any programs because I wanted to get the RAM out ASAP just to make sure nothing would get damaged and came here to ask if using this combination is safe for my PC.

I would also like to quickly ask if there is anyway to see what my motherboard supports for RAM voltage and if/how to change voltage on individual RAM sticks. (If I can combine, that is.)
 
Solution
utroz


I have seen it done. It is not a good idea at all. In the system I saw it on was an HP G6 laptop with an AMD A10-4500M Apu. There was a stick of Dual Rank SODIMM 1.5V 1600Mhz CL11 and a stick of Single Rank SODIMM 1.35V 1600Mhz CL11. A non tech guy put the DDR3L stick (the 1.35V) in the system not knowing and it worked without any problems. Both sticks run at 1.5V 1600Mhz CL11. One again I would not mix ram like that. Sometimes you get lucky and it works and sometimes it does not so always better off to get matched pairs of ram of at least the same specs if you want to add more ram to a system especially if the ram will be working together in a multi channel...
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utroz

utroz

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Nov 9, 2010
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I have seen it done. It is not a good idea at all. In the system I saw it on was an HP G6 laptop with an AMD A10-4500M Apu. There was a stick of Dual Rank SODIMM 1.5V 1600Mhz CL11 and a stick of Single Rank SODIMM 1.35V 1600Mhz CL11. A non tech guy put the DDR3L stick (the 1.35V) in the system not knowing and it worked without any problems. Both sticks run at 1.5V 1600Mhz CL11. One again I would not mix ram like that. Sometimes you get lucky and it works and sometimes it does not so always better off to get matched pairs of ram of at least the same specs if you want to add more ram to a system especially if the ram will be working together in a multi channel config.
 
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TheeAnonymousOne

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Mar 25, 2016
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I think I will pick your answer as the solution, but just curious (not part of my problem), why can 1.5v be overvolted and put with 1.65v? It's a 0.15 difference just like 1.35 and 1.5. Yet 1.35 can't be overvolted and instead would just get damaged. Do you know why?
 
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utroz

utroz

Splendid
Nov 9, 2010
2,184
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21,565


The reason 1.5V and 1.65V RAM tends to work with each other ok is the fact that 1.65V DDR3 RAM is just 1.5V ram factory overclocked and overvolted, so the system usually will run both sticks at 1.65V and the difference between 1.5V and 1.65V is a smaller percent than the difference from 1.35V to 1.5V. And actually I don't think that running 1.35V DDR3 SODIMMS at 1.5V would hurt most sticks. It is a dual channel system with 4 slots I would think that the two 1.35V sticks are connected to one channel while the 1.5V is connected to another allowing the system to be able to run them at different voltages, but I do not known 100% this is just what seems most likely to me.
 
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