My system starts up fine, all icons act properly..

if there's pixilation problems only after 10-20 minutes, i'd say the gpu is overheating.

Now the real problem is if the gpu has been damaged due to the overheating and whats causing it to overheat in the first place.

The heatsinks on the ps3's are crazy so i'd push more towards the gpu failing, but it could be just a simple overheat problem.

They sell external fans for the ps3 that connect to an external power source. Try purchasing one of those, it will run you 30 bucks.

If it continues after that i'd push more towards the gpu's been damaged and your going to need service on it.

Hope this helps.