RAM Upgrade Question - Paired Memory?

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The Bard · #1 Post by **The Bard** » Mon Aug 25, 2008 10:14 pm

I have a T60 with 1GB of RAM and one extra slot. I want to upgrade the memory. An IBM telephone rep told me I should fill the extra slot only with another 1GB memory chip; that is, the memory in each slot should be identical - 1GB in each. I contacted Crucial and was told that's nonsense. What's the truth? Can I pair the 1GB existing memory with another 2GB chip?

Also, is there any reason not to buy the extra memory from Crucial? It's cheaper than the memory sold by Lenovo. I'm guessing that Lenovo doesn't even make the memory they sell. Any advice would be greatly appreciated. Thanks.

s1148625 · #2 Post by **s1148625** » Tue Aug 26, 2008 6:40 am

You can install a 2GB chip - no need to match pairs.

It has been years since I've purchased a RAM upgrade from anyone other than Crucial... their memory will work flawlessly in your T60, and they offer a lifetime warranty on all their memory.

The Bard · #3 Post by **The Bard** » Tue Aug 26, 2008 2:07 pm

Any reason (other than incompetence) why an IBM telephone rep would tell me the opposite? Thanks.

sarbin · #4 Post by **sarbin** » Tue Aug 26, 2008 2:12 pm

well... you said the ibm rep said you "should..." not that you "must...".

the only advantage to installing a matching (speed/size) module is that the memory will run in synchronous dual channel mode. if you install the 2gb module you get asynchronous dual channel mode. there is a slight performance advantage to synch vs asynch, but it's likely outweighed by the advantage of 3gb vs 2gb total memory.

awolfe63 · #5 Post by **awolfe63** » Tue Aug 26, 2008 3:45 pm

My new W500 shipped with 1 1GB SODIMM and 1 2GB SODIMM. It works fine. There is no need to exactly match DIMM sizes. Mismatched DIMMS can cause a 1-2% performance loss - but the extra memory is worth it.

The Bard · #6 Post by **The Bard** » Tue Aug 26, 2008 3:47 pm

Thanks. So the difference between 2GB and 3GB of RAM should be noticable? I don't do any graphically intensive computing, just basic stuff, but I tend to have lots of applications and webpages open at the same time.

awolfe63 · #7 Post by **awolfe63** » Tue Aug 26, 2008 4:27 pm

Probably not. I assumed you were going from 1GB to 3GB.

I find that for the work I do, XP improves up to about 1.5GB and Vista up to 2-2.5GB. Given the current price of memory - I put at least 2GB in every machine.

eecon · #8 Post by **eecon** » Wed Aug 27, 2008 7:35 pm

awolfe63 wrote:My new W500 shipped with 1 1GB SODIMM and 1 2GB SODIMM. It works fine. There is no need to exactly match DIMM sizes. Mismatched DIMMS can cause a 1-2% performance loss - but the extra memory is worth it.

For Vista maybe yes, but for WinXP I beg to differ.

Given the choice under WinXP, I personally would rather have a size matched pair of 1Gb memory modules running in synchronous mode rather than a mismatched pair (1GB and 2GB) of modules running asynchronously.

awolfe63 · #9 Post by **awolfe63** » Wed Aug 27, 2008 8:32 pm

I run one machine at 1+1; one at 2+2; and one at 1+2, all under XP pro. To tell you the truth - there isn't much difference at all.

I would still choose 1+2.

99% of the time - then you are using less than 2GB of RAM it is 1-2% slower. On the rare occasion that you push beyond 2GB, it can be 10x faster than swapping.

eecon · #10 Post by **eecon** » Wed Aug 27, 2008 10:12 pm

awolfe63 wrote:I run one machine at 1+1; one at 2+2; and one at 1+2, all under XP pro. To tell you the truth - there isn't much difference at all.

I would still choose 1+2.

99% of the time - then you are using less than 2GB of RAM it is 1-2% slower. On the rare occasion that you push beyond 2GB, it can be 10x faster than swapping.

I'm probably just being too OCD, like always needing to have matching socks, etc.

awolfe63 · #11 Post by **awolfe63** » Thu Aug 28, 2008 1:19 am

You can get matching socks

pae77 · #12 Post by **pae77** » Sat Aug 30, 2008 2:22 pm

With memory being so cheap these days, I would just go ahead and stick 4 gb (2 -2gb sticks) in. Oh wait . . that's what I already did. But then I'm running V x64 which can (and does sometimes) use all of it.

But if Asynchronous bothers you, I would think that's one potential solution to the issue, unless it would still run asynchronously because only 3 gb were being seen.

eecon · #13 Post by **eecon** » Sat Aug 30, 2008 3:41 pm

pae77 wrote: ...... unless it would still run asynchronously because only 3 gb were being seen.

That is an excellent question!

http://forum.thinkpads.com/viewtopic.php?t=47347

steveg47 · #14 Post by **steveg47** » Sat Aug 30, 2008 5:48 pm

awolfe63 wrote:You can get matching socks

He's probably not married.

pae77 · #15 Post by **pae77** » Sat Aug 30, 2008 6:10 pm

eecon wrote:
pae77 wrote: ...... unless it would still run asynchronously because only 3 gb were being seen.
That is an excellent question!

http://forum.thinkpads.com/viewtopic.php?t=47347

Actually, I'm just guessing w/o researching this, but I bet with 4 gb installed, it would run synchronously when up to 2 gb were being used and asynchronously when more than 2 gb were being used, but that's just a guess. Probably someone who knows for sure will pop in with the answer sometime.

awolfe63 · #16 Post by **awolfe63** » Sun Aug 31, 2008 1:13 pm

That's basically how it works. Theoretically the OS can grab pages in any order and does not need to start using memory "at the bottom" - but the common OSs all do grab pages in the lower 2GB first.

RAM Upgrade Question - Paired Memory?

RAM Upgrade Question - Paired Memory?

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