Newbie questions re X220

[x200_owner]

Hello everybody using ThinkPad!

I became an X220 owner recently and have a bunch of questions regarding it.

1. Memory. Does X220 support 1.35V DDR3? Some users reported that 1.35v is compatible and they have successfully installed 1.35V memory in their X220, but they are not sure whether it is actually working as 1.35 and not 1.5V. So the question is will 1.35V DDR3 work at this voltage in X220?

2. I know that 1 memory module will works slower than 2 modules due to dual channel etc. But on the other hand 1 module consumes less power. So the question is how much slower will 1 module actually be and how big will the power saving benefit be? I'm interested in actual numbers. I've read somewhere about 0.7W profit, would like to hear about other measurements.

3. I have F3507g WAN module from my old X200. But X220 comes with F5521gw. What's the difference between these two cards? Is it worth it to spend ~$80 and buy F5521 instead of F3507, which I already have? Will F5521gw provide better connection? I'm not satisfied with the quality of connecton that F3507gw provides. Sometimes my cellphone can connect to internet using the same ISP, when my X200 fails. GPS quality is also not impressive...

Thanks in advance!

[jcvjcvjcvjcv]

2.) That depends on the used application.

Remember that the Intel graphics uses your RAM too; that might definitely benefit from Dual Channel. 3D Mark score can increase by 50%. I have no idea on the power usage, but 0,7W sounds a bit high to me.