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Hey guys. I have a 3-year old Lenovo G470 laptop which came with 4GB of DDR3-1333 (1 SODIMM, Ramaxel). I thought about putting in another 4GB, so after checking Crucial's website to guide me in making my purchase, I went over to the usual brick & mortar shops in our place. Thing is, many stores told me that while they are selling 4GB DDR3-1333 or -1600 SODIMMs, what they have are low-voltage parts. Now I didn't pay too much attention to Crucial's suggestions before I left home so I wasn't sure about these low-voltage parts and whether or not they'll work with my laptop. Some of them also suggested that I should get standard-voltage DDR3-1333 just to be safe. It was a little tough looking for standard voltage DDR3-1333 but I finally found a seller selling Crucial 4GB DDR3-1333 modules, and so I bought one.

The thing is, I thought these SODIMMs and even desktop long DIMMs are keyed so that users can't go wrong. Is the standards messed up and should people make sure they aren't installing DIMMs or SODIMMs with the wrong voltage? When I got home I rechecked Crucial's web page and I saw that 1.35v parts, which I understand to be the low-voltage variants, are OK for my laptop. I also Googled the part number of the SODIMM I bought and it seems to be 1.5v. So would installing low-voltage DRR3-1333 SODIMMs in a machine that runs standard voltage variants not cause any problems? After all, the Crucial website recommended them and being the memory guys they may be aware that the G470 or other models may come with standard voltage DDR3. Or would installing SODIMMs of different voltages cause problems immediately or later on? Thanks in advance.

The machine should properly detect the voltage and set it on its own, but even if not installing 1.35v kits in a 1.5v machine shouldn't cause any problems. It would just be wasting power and running a little warmer than it should. There might be stability problems if it tried to run a 1.5v rated kit at 1.35, but again the laptop should detect the right voltage.

You don't want to mix and match SODIMMs with different voltages unless your laptop allows you to manually specify to memory voltage. The latop may detect the lower voltage module and use the wrong voltage for the pair. If you mix 1.35 and 1.5v parts you will always need to run both of them at 1.5v.

Thanks for the response. So I was right in getting a standard voltage 1.5v SODIMM? My laptop doesn't have RAM voltage settings in the BIOS.

Check the specs, but I recall that at least some/many/most DDR3L modules are also specced to support 1.5V. I'd expect any laptop that supports 1.35V DDR3L to also support standard 1.5V, but I could be wrong. So my impression is that you can hardly go wrong whatever you choose.

Micron specs for MT41K1G4, MT41K512M8, MT41K256M16:
• Backward compatible to V DD = V DDQ = 1.5V ±0.075V

Samsung K4B2G0446D, K4B2G0846D:
• JEDEC standard 1.35V(1.28V~1.45V) & 1.5V(1.425V~1.575V)

Hynix H5TC2G83CFR, H5TC2G43CFR:
"SK hynix DDR3L SDRAM provides backward compatibility with the 1.5V DDR3 based environment without any changes"

Hynix HMT425S6MFR6A, HMT451S6MFR8A, HMT41GS6MFR8A:
"Under 1.5V operation, this DDR3L device operates to the DDR3 specifications under the same speed timings as defined for this device."

Winbond W631GU6KB:
• Backward compatible to Vdd, Vddq = 1.5V ± 0.075V

Ok. I guess it's best to stick with the specs of what's installed, just to be sure.

Kougar wrote:

You don't want to mix and match SODIMMs with different voltages unless your laptop allows you to manually specify to memory voltage. The latop may detect the lower voltage module and use the wrong voltage for the pair. If you mix 1.35 and 1.5v parts you will always need to run both of them at 1.5v.

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This is right. Don't mix them just in case. Some motherboard manufacturers/chipsets aren't created equal and are not smart enough to handle 2 different voltages. If you can swing it, buy a 2x8GB kit, go for low voltage ones which typically are better quality, use less power and put out less heat. Sometimes the 1.5v DIMMS are just sticks that couldn't run stable at the 1.35v, and vice verse.

Most laptops unless high end will not let you set these manually, they read the factory settings from the SPD on the memory itself.