Thinkpads Forum

Hi Folks,

I currently have a Samsung 4GB memory chip PC3-8500F (part number M471B5273BH1-CF8) in one of my slots. There seems to be an equivalent chip for sale on ebay here: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0500970952 . Anyone know if the ebay chip would be "equivalent enough" to allow for dual data rate operation?

thanks!

If you are asking about "dual-channel" mode (slightly speedier memory accesses), then, yes, that eBay module will probably work. PC3-8500 is a standard timing spec and all modules labelled that way should perform the same. But if the memory architecture of the modules are not the same (number of banks or sides) then the memory controller might not be able to handle them in dual-channel mode. It's usually recommended to install matched pairs to be safe but realistically, IMO, the 5 to 10% increase in performance will not be noticeable when surfing the web or running normal office suites. You will probably see the effect when running a benchmark test but I'd be surprised if you detect any increase in frame rates when playing any games or reduction in time when calculating a huge Excel spreadsheet.

ref: http://en.wikipedia.org/wiki/Multi-chan ... chitecture

thanks for the reply, rkawakami. I run statistical models on my machine that often take up to an hour to roll through code loops and stuff like that. I'm not sure if dual-channel mode (thanks for the vocab correction) will be too noticeable an improvement, but perhaps $20 isn't too much to risk for a small improvement?

Any idea how I check the equivalency of banks and sides?

thanks again!

UPDATE: I just bought the same exact chip for $24, so no worries. Thanks again.

In general, the more the memory, the better; as long as your hardware and OS can support it. Even if your system does not implement dual-channel mode, the additional memory should help reduce the amount of swapping (i.e., paging or virtual memory) that can occur.

Banks or sides can be determined by counting the number of individual chips on the module, or consulting the datasheets supplied by the manufacturers. If they are both 4GB and both have 8 chips on them, then they should have the same architecture.