Determine if my CPU has damage/is fried [pics]

I made a new setup with an E8400 (LGA775) for the following setup:

Heatsink: Arctic Freezer 7 Pro
MB: Gigabyte GA-P35C-DS3R
RAM: 2x2GB Corsair XMS2 DHX
PSU: Corsair HX620W (EU)
Case: Coolermaster 690

http://i27.tinypic.com/350ut6o.jpg

(see what looks like dark marks - normal?)

I checked everything before turning anything on, and everything was alright (checked it afterwards as well to confirm, and indeed no errors).

But one thing I didnt think much of, was that I had accidentally turned the computer on before this, having forgotten the motherboard standoffs (as it is rarely needed with the computers I normally assemble, and thus I had no attention towards it). I powered on a few times with this mistake, with nothing happened (no power to MB, because it was shorted out by touching the case metal).

I figured this out, and put the standoffs on, and indeed everything worked, and everything else was perfectly setup and working well. I used to work "professionally" with assembling computers, and there, the standard test for whether the CPU was working, was if the MB would actually POST, and if the operating system started up - and here, it does.

However, I fear the CPU has damage, and I dont know how I would know, as the computer starts up.

So tell me, considering that the CPU has worked so far, does it have damage? Is this slightly deeper color in some areas merely superficial, and a result of power going through it/usage? Or does it mean the CPU is fried?