Is RAM upgradation in imac restricted to 4 GB only

I have got a imac , I was facing a bit of slow performance issue in my portable device , so one my my colleague had recommended me to upgrade the RAM , I already had installed 1 GB of RAM in it , I decided to upgrade it to 4 GB , but I have removed the 1 GB RAM stick that was installed previously , my question is that can I install the spare RAM stick in another RAM slot and make it 5 GB of RAM , I am asking you because I have heard that there are certain restrictions regarding the RAM upgrade in imac and you cannot exceed it from 4 GB . Is it true ?

Sorry to talk a bit off topic but there could have been some other reasons as well for that slow performance , nevertheless there is no point returning back as you have already purchased a RAM stick of 4 GB . Well coming back to your doubt I do not think that there are any sort of RAM upgrade restrictions but still you can test it if you want , you can test my placing the 1GB RAM stick in hat additional slot and check whether it works or not.

If you check the Specification article in the Apple forums for imacs you will come to know a bit about it , it states that you can make use of a 1 or 2 GB module in each slot. If your iMac is not this model, you should go after Apple's specifications. If your imac is working with a 4 GB stick in one slot, very well, but I would not have gone after this it. Additionally, RAM modules must be upgraded in even number configurations (2, 4, 6 etc.) - not 5.

I am content with the scheme of 4 GB RAM stick and a 2 GB RAM stick being used all together , but I do not remember that a upgradation being done with a 4 GB RAM and 1 GB Ram with you about the 4+2, I don not 't remember having seen an uneven figure of Gb either. But I have heard and it is being stated that upgrades can be done in uneven figures. So you should do as you wishSince the 6 GB kit would be less expensive than a 4 and a 2 GB individually, maybe you can have a word with them into selling you the kit and you give back the 4 GB? Just a suggestion , rest is upto you .