Question about DDR3 memory and Dual channel

[Pharos]

I upgraded my late '09 13" MBP to 4gb, but one of the sticks apparently died. I'm about to replace it with my old 1gb stick so then I'll have 3gb total ram.

Will this turn off dual channel mode? If so, is it noticeably slower?

I use my laptop for very basic stuff. I have my desktop for more intensive tasks. Am I better off putting back my 2x1gb sticks, or is the 1gb + 2gb combination OK?

Thanks

 

[Hellhammer]

For the best performance, you should use two identical modules. Dual-channeling will only give a boost of ~5% so just ignore it.

BTW, most RAM modules come with lifetime warranty so give the manufacturer a call

 

[m85476585]

It will go into asymmetric dual channel mode, so the first 2gb will run at dual channel, and the last 1gb will run single channel. You are not likely to notice the difference, and the fact that you have 1gb less RAM will probably cause more of a performance hit. If you run out of RAM and the hard drive has to be used for swap, the computer will slow to a crawl and beachball while stuff is being swapped out.