Ok so a few of you may know I've been having troubles with my newly built computer.

conclusion was that the motherboard was screwed and I'm waiting for it to be collected now for an exchange.

My new question is that will I have to re-apply the thermal paste to the cpu/heatsink.

If so, what do I do, do I clean off the existing paste? or just add a bit more? or leave it as it is?

If I have to clean it what do I use?

This is what state it is currently in: