Hello all, I realise this is a common problem, but my situation seems to be a little different. I'll try and keep this short while giving all the details. Would really appreciate any help. I ordered a 4gb RAM upgrade from crucial.com/uk for my dads 2007 iMac, which came with 1gb standard. The new memory doesn't work! The existing RAM stick is a 1gb 667 PC2 5300. However, and here is where my problem differs from the others - so is the crucial memory I just received. Like many people, I've tried with the existing stick, and just one of the new 2gb sticks, and it works, giving 3gb. It doesn't work with both slots filled with the new sticks, or with a new stick in just one of the slots. The computer starts, but no gong sound, and nothing happens on screen - it remains blank. I actually ordered through the crucial RAM tool, and got this. Any help much appreciated folks!