Soft creaking sounds coming from mobo\cpu area.

[litwicki22]

Intermittently, there will be a sound coming from inside the computer that sounds like a slight creak, not high pitched but sort of like when you step on a wooden floorboard. This usually happens as the system is coming out of load or going into load. I wouldn't be that worried about it normally, but since it hasn't happened before I'm wondering what could be causing it.
Noise is coming from near cpu fan.
Could the motherboard or cpu fan be "warping" from the heat? Is this normal?

Edit: A more akin comparison might be to a car that has just turned off, and the engine makes kind of sporadic ticking noises as it cools off. Just wondering if computers could make this noise as well (but not as loud).

my pc is:
Asus Sabertooth Z97 Mark 2
8gb ram
4790K
Corsair 750 RM
Inno IChill 980 Ti ultra 3x

 

[Sabrewings]

http://forums.anandtech.com/showthread.php?t=2440846&highlight=

 

[Ramses]

My Z97-WS in an FT02 does that bigtime, previous 990FX board did as well so I assume it's this giant heavy metal case heating and cooling. It's more pronounced when it's really chilly ambient. I dig it, sounds much like a car exhaust cooling off.