Does ram configuration matter?

[mike.coulter]

Hi everyone, I've recently purchased a compatible stick of ram for my late 2009 iMac 21.5", but its 4GB in one, not 2x2GB.

Seing as there are 4 slots, 2 containing 2x2GB, is it okay to fill the third with just a 4GB rather than use all the same sizes and have 4x2GB?

Thanks, Mike.

 

[AcesHigh87]

It is and it isn't. iMacs are designed as dual channel which means they work best with paired memory. Given that you're only putting in one stick it will change the iMac to single channel. Since its still a 4Gb upgrade you likely would still notice it be faster than before but it won't be as fast as it would if you added 2 more sticks of 2gb a piece.

 

[mike.coulter]

It is and it isn't. iMacs are designed as dual channel which means they work best with paired memory. Given that you're only putting in one stick it will change the iMac to single channel. Since its still a 4Gb upgrade you likely would still notice it be faster than before but it won't be as fast as it would if you added 2 more sticks of 2gb a piece.

I suppose I could buy another stick of 4GB somewhere to balance that out and sell my other 2GB ones...

 

[leman]

You can try it out and see if it works for you. The real-time performance between single and dual channel configurations is close to zero AFAIK, so it shouldn't be your main concern. However, it is possible that the CPU will do "strange things"(tm) wich such configuration. Mine used to crash occasionally when I mixed the 4GB stock RAM and 8GB aftermarket Corsair RAM (although many users reported that particular RAM working fine). I have removed the stock 4GB and the Corsair RAM has been running stable ever since. My point: you can always get lucky (in the negative sense).

 

[alust2013]

You will always benefit from more RAM over having less in a dual channel configuration, unless you don't need the extra memory at all. It's basically impossible to see the difference between single and dual channel unless you're moving huge amounts of data anyhow

 

[cyberioten]

I use Kingstons tool to find the ram and correct specs. See http://www.ec.kingston.com/ecom/configurator_new/mfrmod.asp?root=us&LinkBack=http://www.kingston.com