W510 Adding RAM

I have a w510 with four memory slot locations (2 under keyboard and 2 accessed from back). It has the original 4 GB of memory. It has two 2 GB memory cards under the keyboard. I want to buy two 4 GB memory cards. I watched a Lenovo video and it said that the larger cards should be in slots 0 and 1, under the keyboard. So I assume that means that I have to remove the two 2 GB cards that are currently in 0 and 1, and replace them with the new two 4 GB cards.

1) is that correct, or can I put those new 4 GB cards in the open slots on the bottom?
2) if I put the two 4 GB cards in the top slots, 0 and 1, can I put the older two 2 GB cards into the bottom slots to get a total of 12 GB?
3) the current old RAM is 1Rx8 PC3 8500S-7-1-B1. Will that work with the new RAM that I intend to buy? Or will the older RAM slow down the newer RAM.

NEW = Module Size: 8GB Kit (4GBx2)
Package: 204-pin SODIMM
Feature: DDR3 PC3-10600
Specs: DDR3 PC3-10600 • CL=9 • Unbuffered • NON-ECC • DDR3-1333 • 1.35V • 512Meg x 64 •

 

You can just add the new cards. No need to remove the old ones.

Yes.

It should work, and the new RAM will downclock to the PC3-8500 speeds. Not sure about the 1.35V bit, though.

Ultimately, it's the speed of your planar's FSB - which you have no control over - that will determine the RAM speed, not the sticks itself. This ThinkPad will always run at 1066 speeds.

 

So will I see the effect of the downclock to the PC3-8500 on the ThinkPad's bus? I am running Solidworks and I am buying this extra RAM because with currently only 4 GB of RAM I am running out of RAM on large assembly files. But I don't see myself needing more than 8 GB, so I'd rather get faster RAM times for assembly rebuilds than have more than 8 GB of RAM. In other words, should I not install the slower PC3-8500 RAM if I want to make the computer run faster, OR is the ThinkPad already limited by the ThinkPad's bus? - Once i get everything installed and running I will benchmark with and without the slower extra 4 GB and then report results here.

 

Your machine is already limited by the speed of planar, not RAM. The "slower" RAM matches the motherboard speed and there's nothing the "faster" RAM can do to enhance performance, with or without its "slower" sibling.

Hope this clears any confusion.