512 and 1 gig ram work together right?

[snorlax360]

I might order a 1 gig ram. Does it work with a 512? what i mean is, if i have a 512 stick and a 1 gig stick. will they work together or it has to be the same

[pianowizard]

They usually work together fine. My Dell Inspiron 6000 has one 1GB and one 512MB PC2-4200 sticks, and the R50p that I should receive next Monday has one 1GB and one 512MB PC-2700 sticks. I've been using the former for 9 months without any issues, and according to the seller the latter works perfectly fine too.

[SHoTTa35]

doesn't matter what size they are, they'll work together. I don't know about Dual Channel mode tho if that's what you were really asking about. Dual Channel mode i think needs 2 RAM sticks of the same size and speed (or it'll just drop the faster one to match the slower one)

My Thinkpad T42 has 1GB and a 512MB of DDR333 and they work just fine, i'll be upgrading soon to 2GB total.

(Anyone needing 2 x 512MB DDR333 should email me or PM I'll prolly list them for sale as soon as i get my 1GB stick)

[XIII]

They will work in dual channel mode but it is not as good as dual channel mode with two memstick of the same density.

[wallybear]

Two RAM modules of the same size and speed ratings are needed to enable Dual Channel mode. Your plan to use two unequal modules will result in the memory subsystem running in Single Channel mode.

Dual Channel mode means that the "path" to the entire memory "space" (such as 1GB or 2GB total) is twice as wide as the path to one module (half the entire space such as 512MB or 1GB).

In other words, think of Dual Channel as taking both sides of the road (left and right) to send data along at one time. Whereas Single Channel can send data along only one side of the road at one time.

Dual mode doubles the "roadway" or path to RAM. The improvement in benchmark tests is only about 10% or so (meaning that it's very hard to tell the difference between the modes).

I hope this helps. Questions? Write to me...

[Redmumba]

So in conclusion, yes, the 512 stick and 1024 stick WILL work together, but will not operate in dual-channel mode (for the above mentioned reasons).

But why not just upgrade to 2x1GB sticks? At ~$40 a pop for a stick, I'd say its worth upgrading, since it won't exactly break the bank.

[RonS]

Having two DIMMS exactly the same will allow your system to run in Symmetric Dual-Channel mode.

If your memory DIMMS are mismatched, then you systems runs in Asymmetric Dual-Channel mode.

So, three modes are supported:

1. Single channel.
2. Dual-channel symmetric. This is the fastest mode. Both memory modules must be the same size.
3. Dual-channel asymmetric. Performance is just slightly better than single-channel.

It's possible to run asymmetric with one memory module, but I don't know if the Thinkpad supports that mode.

http://www.intel.com/design/mobile/datashts/309219.htm
see page 337

[Redmumba]

Having two DIMMS exactly the same will allow your system to run in Symmetric Dual-Channel mode.

If your memory DIMMS are mismatched, then you systems runs in Asymmetric Dual-Channel mode.

So, three modes are supported:

1. Single channel.
2. Dual-channel symmetric. This is the fastest mode. Both memory modules must be the same size.
3. Dual-channel asymmetric. Performance is just slightly better than single-channel.

It's possible to run asymmetric with one memory module, but I don't know if the Thinkpad supports that mode.

http://www.intel.com/design/mobile/datashts/309219.htm
see page 337

Asymmetric is typically only using one channel, due to the fact that you're unlikely to be requesting data from both chips at once. So its really only single-channel + a minor boost.