T420i - from 4gb to 8gb ram - which Crucial?

[jazzfido]

Soon to be a second time owner of a Thinkpad (the first one was in the beginning of the 1990s, so only a distant memory). It is a T420i with 4gb of ram, bought second hand (yet to arrive). My plan is to upgrade to 8gb using Crucial ram. I assume that the existing 4gb of ram are occupying only one memory slot.

I have to get the ram from the UK, and I would like to minimise the cost of the upgrade. On Crucial's website the following is identified as a guaranteed fit:

CT3320752: http://www.crucial.com/uk/store/mpartsp ... 44A5CA7304

However, the following two seem closely related, and are easier to buy in the UK:

CT51264BF1339: http://www.crucial.com/uk/store/partspe ... 1264BF1339
CT51264BC1339 http://www.crucial.com/uk/store/partspe ... 1264BC1339

Does anyone have any experience with these latter models in the T420 or T420i? Will they work satisfactorily? Thanks in advance.

[ZaZ]

Unlike the gold old days ThinkPads are not very picky about which memory they will accept. I would buy whatever is the least expensive from a good brand. The chances it'll fail are fairly low, though not zero.

[jazzfido]

Thanks!

And is the difference between 1.35v and 1.5v (with 1.35v recommended for the T420) likely to be an issue? Most available ram seems to be 1.5v.

[ZaZ]

It's unlikely you'd notice a difference outside of the benchmarks.