laptop - 1.35 V RAM in a 1.5 V system - Will it fry or overclock?

The general question is:
When installing low voltage RAM in a board that outputs a higher voltage to the memory module, will this fry the RAM or will it be like overclocking it?

My specific case is:
I have the Alienware m17xR3 laptop with a 2630QM Sandy Bridge board. Currently, I have the stock 1.5 V modules and when I check the overclocking options in my bios, the RAM voltage option ranges from 1.5 - 1.65 V. Is this simply because the bios recognizes that these are the values which my current RAM support and thus they will change when I install 1.35 V RAM or will I have to run the 1.35 V sticks at minimum 1.5 V?

If the case is the latter, would I fry my 1.35 V sticks? Or would they become automatically overclocked and get tighter timings with a higher voltage? Or both? Or neither? I'm a bit lost :p

Answer

1.5V is the JEDEC standard for DDR3, therefore you will never fry a module at this voltage.

Some sources:

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  Hynix: "Hynix DDR3L SDRAM provides backward compatibility with the 1.5V DDR3"

  
  


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  Crucial refers to this as Dual Voltage: In the past, most DDR3 memory voltage ranged from 1.5 - 1.65v. More recently, dual 1.35/1.5 voltage modules came available at Crucial.com. The dual-voltage module will run only run at 1.35V if your specific system supports that voltage, otherwise the memory will run at 1.5V.

  
  


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  Kingston: As DRAM manufacturers shrink their dies and/or increase their yields of DDR3L, they soon reach a point where the majority of their DRAM output becomes DDR3L or dual-voltage, handling 1.5V or 1.35V voltages.

  
  

DDR3L (low-voltage DDR3) is just an "extension" of the DDR3 standard, so companies has to be aware that plugging a module will default to 1.5V on most systems. At 1.5V, the worst that will happen will be a waste of electricity/battery.

RAM modules contain pre-defined configurations (SPD, XMP, etc.) but the default one is often safer value that will work on as many systems as possible. For compatibility purposes, that setting might not be factory-set to 1.35V, but 1.5V instead. The default timings can also be different and slower from the ones indicated on your module package (I have an other answer on this topic).

For this reason, there's no chance it will overclock by itself even if it's running at a higher voltage (unless your current BIOS settings are manually set to run at specific speeds higher than your new modules would support - if so, reset your memory settings to AUTO before installing them).

If your RAM contains a XMP profile, try that as it can be factory set to 1.35 and all ideal settings - but you still have to select it manually in the BIOS.

In conclusion, 1.35V is perfectly safe. It's still always a good idea after installing RAM to go in the BIOS and verify/adjust the settings to ensure they match the module packages and perform optimally.