Did you install any accessories and/or apps before the crash?

You can try booting into Verbose mode and see where & what cause the freeze.

First have you try place back the stock RAM?
Does it work? If no then move on.

Put in the DVD came with your Mac, hold down C then power on. See if that boot.
If yes, then your boot volume is not booting, need repair or reinstallation If no it could be hardware related.

This post has been edited by wei: Feb 20 2011, 01:06 PM

3. Please confirm you are booting from the DVD. Sometime it will boot from the HDD if you did not press "C" soon enough or let go too early.

Insert the DVD and restart/re-power on holding Options (alt) key. You should see similar screen like this (but with less icons):


Select the DVD icon to boot.

This post has been edited by wei: Feb 20 2011, 01:15 PM

Keep holding Option (alt) when you power on/restart. Until you see similar screen I posted. Let go. Choose the DVD to boot. You can also put in the DVD during that screen and wait the new icon pop ups.

No, Apple is known to use Samsung, Micron & Hynix for stock RAM. Never Kingston (unless in early PPC era). KTA is trusted DIY upgrade option.

This post has been edited by wei: Feb 21 2011, 10:28 AM

Almost all big brand will have Apple RAM. Crucial, corsair, kingston, micron, mushkin, OCZ... Just that, can you get them here or not.