I hope this is the right place to ask, but if not fell free to move this query.

Every mother board for a Turion 64 X2 that I have seen has room for two memory sticks.
Almost every system is sold with both slots filled, rather than one filled with a larger memory
and one empty. This saves some money for both the seller and the buyer at the time of sale.
But the buyer has to discard at least one stick to upgrade later.

What are the performance effects of one stick instead of two, or of different sizes of memories in the two slots?

If I understand the design correctly I suspect some benchmarks will show one stick is slightly more than
half he speed of two, and some other benchmarks will show one stick is the same speed as two, or even just a tiny bit faster. I suspect the second stick helps when two or more programs are actively running at the same time.

Real numeric results with well defined workloads would be most useful, but even predictions with explanations would be nice.

Thanks.

My own Asus A6T came with only one. Better brands come with one stick (at least ive seen several A6 series with one stick, both AMD as Intel). 2x 512MB is faster then 1x 1GB as it uses dualchannel. But 1x 1Gb gives more options to upgrade (cheaper). It is one of teh things ive looked at buying a laptop as i already did upgrade to 2GB (works perfect in Vista ). My Vista Mem rating got from 4.5(1GB) to an 5.4 (2GB duaclchannel).

To see wether your laptop has 1 or 2 modules without screwing teh backside open you should download this program. Fast and easy, check teh memory tab:
www.cpuid.com/cpuz