Ram upgrade 2x2 vs 2x4

[Acer7740]

So i want to upgrade my ram from 2x2 to 2x4 for gaming purposes. My laptop is Acer 7740g with 2 modules of Elpida 2GB DDR3 1066, PC3-8500s, 533 clock speed (Jedec), 1.5V, SO DIMM

I cant find 2x4gb with exact the same specifications, so my questions are:

-12800s or 10600 vs 8500s is it compatible?
-1066 vs 1333 or 1600 is it ok?
-1.5 v vs 1.35v
-is it possible to have different pin than 240?

My chipset is Mobile Intel HM55

Thanks

 

[Sakkura]

PC3-12800 = DDR3-1600
PC3-10600 = DDR3-1333
PC3-8500 = DDR3-1066

They are compatible in the sense that a faster kit will be able to run at lower speeds if that's all the computer supports.

Voltage depends on what the system supports. Most likely both 1.35V and 1.5V are okay.

DDR3 SO-DIMMs have 204 pins. 240 pins is found on DDR3 DIMMs, ie. memory for desktops.

 

[Acer7740]

Maximum support is as follows:
PC3-8500
DDR3-1066
Rammon says that Module voltage is 1.5 so i don`t know if that is current or maximum supported.

I have found these at a pretty decent price: Samsung 4GB PC3l-12800S DDR3 1600 Sodimm. Are they all right?

Pin was 204, my fault

Also is there a difference between PC3 and PC3L

 

[Sakkura]

PC3L indicates low voltage, 1.35V.

It should work. Might be a bit fiddly to set up manually though, if the memory doesn't have SPD for the slower speed your system needs.