RAM speed & latency options quandry

My laptop came with 4GB RAM -- 2x2GB DDR3 1066 PC8500 CAS-7 -- and it has 4 SODIMM slots (Lenovo W510 laptop). I want to add additional memory. My options are these:

1) Simply add 2 additional similar modules; or,
2) Replace the existing modules with 2x4GB modules.

If I replace, I have two options:
2A) replace with 2x4GB DDR3 1066 PC8500 CAS-7 modules; or,
2B) replace with 2x4GB DDR3 1333 PC10666 CAS-9 modules.

Options 2A and 2B are essentially the same cost, so money is not the consideration. My primary use of the computer is memory intensive (rendering images, video, autocad, etc). According to its specs, the W510 works with either memory speed. It seems to me that I might be better off with the DDR 1333 memory; however, I don't know how the difference in latency (CAS-9 as opposed to CAS-7) affects performance.

There are also 3rd and 4th options: I could replace the existing SODIMMs with 4x2GB DDR3 1333 PC10666 CAS-7 modules, giving me 8GB of 1333 speed and CAS-7 latency or I could get 4x2GB DDR3 1066 PC8500 CAS-5 modules, keeping the same memory speed I have currently but reducing latency by 2.

Adding to the confusion, I understand that latency if further degraded by having 4 modules as opposed to only 2 modules.

Can anyone explain the implications of the various options? Thanks.

 

If you want more memory, stick with option 1 and buy two 2GB or 4GB modules to add to what you have. Get whatever frequency and timings are cheapest because it is all the same. Don't worry about 1333 vs 1066 or cas 7 vs cas 9. All a non-issue and completely irrelevant. All the memory modules will work together just fine and run at the same frequency and timings.

 

to add...

you will not be able to tell the difference between cas 7-9 and there will be no noticeable increase in performance...


IDK about 1333 VS 1066, maybe if your laptop can handle faster memory...

 

Memory speed and timings both don't make much difference in overall performance, especially when compared with adding more memory for those programs that can utilize it. I would go with adding two similar modules (unless you find 1333MHz modules cheaper, whereas it would just downclock to your current speeds to match them).

 

Thirded. Just add to your memory, fill the empty slots before you start thinking about replacing RAM. You could get 2x4GB and triple your memory.

The performance difference between 1066 and 1333 is almost negligible, especially compared to the benefits of extra memory. Note also that only quad-core i7's can take DDR3-1333. Core i5's and the dual-core i7's are limited to 1066 (and will clock 1333 down to 1066), so depending on your processor it may not matter.

 

Thanks for the assist, guys.