RAM upgrade better in identical pairs?

Just received the 2x2GB ram. It says to benefit from the performance advantages offered by dual channel systems, it's better to install memory in identical pairs. How much difference does it make? I have 1GB and want to add 2GB (keeping the other 2GB for the new x61s).

To add (be adviced I'm a newbie in adding ram myself ):
There are 2 small labels on the ram, one says "removal will void warranty". Am I supposed to keep the labels on when installing it?

 

Will void warranty? Can it work if keep the labels?

 

LOL, keep the labels on it... there is no reason to remove those labels unless you were going to install a RAM heatsink on that side (and you won't be doing it on your laptop). The labels will not prevent the RAM from working and will have no ill effects on the RAM or your laptop. If you were REALLY bothered by them, I would install them, let them run for a couple of weeks to make sure there weren't any problems, then take them off if you want.

 

Thanks How much "better performance" is gained by two identical pairs?

 

Keep the sticker, there's no harm in it. My laptop has stickers on both sticks of RAM.

There is a small performance advantage to installing identical sticks of RAM in both slots, but from the benchmarks I've seen, it's not really noticable. A bigger concern is whether you have a 64-bit operating system (which you most likely do not have) - if you install 4GB of RAM without a 64-bit operating system, your computer will only be able to utilize ~3.5GB of it. I suggest you just replace one of your memory sticks, for a total of 3GB of RAM; don't worry about having 2 identical sticks of RAM.

 

Yeah, if you can get a good deal on two identical sticks then go for it, but if not don't sweat it.

 

Thanks Midnightsun and Tabbed out As you guessed I have 32-bit. I't now has 1GB 1DIMM, so adding a 2GB should be the best thing to do for me I guess (besides, it's Win XP, not Vista)

 

The labels are there for authentication purposes.

If I were to go round buying 2nd hand rams, I sure want to see the rams are from a geniune source.

 

I've just upgraded my memory from 2GB (2x1GB) to 3GB (1GBx2GB) and Vista now runs noticeably faster. But from the 'All CPU meter' gadget I only see that my memory is ~2.5 GB in total. I assume the integrated graphic card has used ~0.5GB RAM shared from the system memory. Therefore, I think if you buy a pair of 2GB memory sticks and you use integrated graphic then it will be the best option, because as MidnightSun said above, 32-bit OS can only 'see' at most ~3.5 GB RAM.

 

I'm with TabbedOut.

But let's define identical just to be sure.

RAM can vary by size, speed rating and timing. I think most have answered "same size == identical." In this case, you can gain a slight speed advantage (interleaved operation) when same size RAM sticks are used. This will be on the order of a couple percent and not worth losing sleep over.

If you buy faster or slower speed rated RAM, then I think that all RAM will operate at the slower speed rating, but no faster than the laptop can handle in the first place. For example, This T42 uses PC2700 RAM and if I put PC3200 RAM in it, It would still operate at PC2700 Speed. If you add a stick of PC2100 to the existing PC2700 I'm pretty sure that all RAM will operate at PC2100 and may noticeably slow your system. (In fact, I have tried using PC3200 in this T42 and it does not work, but I think that may be a voltage issue more than a speed issue.)

Among the same speed ratings, there are differences in timing (CAS latency.) Again, I'm pretty sure all RAM will operate at the same CAS latency so adding RAM with higher latency (slower speed) could slow all RAM down. I think this also falls into the range of a couple of percent and may not be noticed by most users.

I hope this helps,
hank