just installed new memory and i have a few ?'s

i recently bought 1x2GB and 2x1GB RAM. i installed 3GB on my dv6000t and i put the 1GB on my sister's dv9000z so now she has 1.5GB. i ran MemTest and both works fine. i do have a couple of questions after i checked our CPU-Z...

1) it shows that mine is working Dual Channels even though it's different kinds of RAM, and my sister's shows Single. from what i understand the RAM should be the same in order to run dual channels. i'm not complaining or anything but does anyone know why this is the case?
2) the 2GB RAM is 5-5-5-15, but on CPU-Z under the Memory tab it shows as 4-4-4-12. i was thinking maybe it's the 1GB stick that's causing this, but my sister's shows 5-5-5-15. but on the SPD tab under Timings Table 333MHz, it shows 5-5-5-15 for both RAM modules. should i even be worried with this?


Thanks in advance.

 

1) It is not always the case that the RAM sticks need to match. There are exceptions, although it might have some stability and speed issues.

2) The confusion by CPU-Z might have been caused by 1). It should be nothing to be worried about, lower CAS latency is preferred after all.

 

CPU-Z seems to be very tolerant about dual channel. I wouldn't worry about what it says. It is better to measure the memory performance using benchmarking software such as Sandra. On various notebooks I have seen no more than about 10% diffference in memory data rates between two identical modules (which should be dual channel) and having only one of those module (which should be single channel).

John

 

Depending on the chipset ie. 965, 945 etc Intel supports dual-channel memory mode in three different fashions.

1- Interleaved dual-channel has matcing size dimms
2-Flex Mode dual-channel, 1 dimm larger than other, so if a 2g w/ a 1g only 2g runs in dual channel the other 1g, off the larger 2 gig stick runs in single mode
3- single-1stick of memory

Link explains more in depth http://www.intel.com/support/motherboards/desktop/sb/CS-011965.htm