Is it a problem if memory sticks are operating at different voltages (1.5v and 1.35v) (laptop)?

Dipak C

Reputable
Oct 16, 2014
4
0
4,510
Hi all,

I just installed a new 4gb Crucial-brand SODIMM in my Lenovo X220 (64bit i5) after confirming compatibility. Is it okay that the two SODIMMs are operating at different voltages? The old one is operating at 1.5v and the new one is running at 1.35v as can be seen in exhibits 1 - 3 below.

My understanding was that despite the fact that the new stick's latency is better (i.e., higher Mhz) than that of the old stick (CL11 vs. CL9), the smart fellow in my computer would correctly adjust by simply choosing to run both sticks at the lower speed. Is it incorrect to apply a similar logic to voltages?

My suspicion is that it's probably fine given the computer booted and the OS is correctly seeing the amount of installed memory (as per exhibit 4 below)...BUT I'm paranoid so I wanted to make sure. Do you see any issues with my current set-up based on the CPU-Z info (included below)?

Thanks!

Exhibit 1: CPU-z 'Memory' tab
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Exhibit 2: CPU-z 'SPD' tab, Slot #1
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Exhibit 3: CPU-z 'SPD' tab, Slot #2
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Exhibit 4: My Computer --> Properties



*end of post*


 
Solution
both sticks are running at the same voltage . you cant run them at difference voltages at the same time. micron adjusts to 1.5v and 666mhz to much samsung's specs! and yeah you're lucky!



I am a bit surprised, but, since it is working, apparently you are ok.
You can run memtest86+ to verify that all is well.

I think a ram controller needs to manage all ram with the same specs of speed, timings, and voltage.
If they are different, the ram will operate at the slower of the individual stick capabilities
 

RealBeast

Titan
Moderator
I suspect that both sticks are running at 1.5V, as I have not seen a bios that could run using two different voltages and the 1.5V would probably not work at 1.35V. CPU-z just lists the SPD values not the actual Vdimm that the board is running. Both meet the DDR3 specs so 1.5V should be fine.
 

Dipak C

Reputable
Oct 16, 2014
4
0
4,510
Thanks everyone. Not surprisingly, you're correct - the voltage stat in CPU-Z is not indicative of the voltage that a stick is currently drawing.

Memtest86 passed all tests successfully (including test #10, i.e., bit fade), reporting zero errors....so I did indeed get lucky!

If curious, I came across the following after I posted: As confirmed by Crucial (link below), in order for a dual 1.35V/1.50V memory stick to operate at the lower voltage, both of the following factors must be true: (i) the system (i.e., motherboard) must be capable of supporting the lower voltage and (ii) all other memory sticks in the system must be able to operate at 1.35V. If even one of these conditions doesn't hold, the memory stick will operate at 1.50V.

To readers: probably best to do a brand-specific analysis before purchasing memory (i.e., its a bad idea to first install the new stick and then look into potential voltage issues, which is what I did...)

Crucial link: http://forum.crucial.com/t5/Crucial-memory-for-PC-systems/1-35v-1-5v-Dual-Voltage-DDR3-memory/ta-p/71731