Strange bangs shortly after PC is switched off

[deathsqaud3]

I've been looking for a cause to this situation for quite some time now, however I don't believe it's much of a problem as it's been happening for as long as I can remember with no noticeable negative effects. Basically when I switch my PC off after it's been running all day it starts to let off a banging noise with variable loudness and at random intervals (usually 3+ times up to an hour or so after it's been powered off). I've always thought it was heated plastic or metal rapidly cooling down after being X temperature all day and the noise was the material returning to room temperature.

(Imagine the noise being like hitting thin layer of plastic with a small metal rod, poor description I know lol)

Does anyone else experience this or know about it? If so any insight would be greatful, thanks!

 

[HowNowBrownCow]

what kind of hardware is in the PC?

 

[Codrru]

partly what you think, high heat followed by cooling, but most likely it is also combined with the case having either too much pressure or too negative pressure. maybe adjust some fans to balance so it is only partially positive pressure inside and check the temps if those check out then come back and we will try to help answer this question further.

 

[deathsqaud3]

Hardware:
CPU: i7-3770k
GPU: GTX 980 EVGA Classified
Case: NZXT Phantom (full tower)
Cooler: Corsair H100i
RAM: 16GB Corsair low profile
Mobo: Asus P8Z77
PSU: Corsair 850RM (80 plus gold)
HDD: Seagate barracuda 1TB (x2)
SSD: Samsung 840 PRO 128GB

 

[Codrru]

what is your fan setup

 

[deathsqaud3]

partly what you think, high heat followed by cooling, but most likely it is also combined with the case having either too much pressure or too negative pressure. maybe adjust some fans to balance so it is only partially positive pressure inside and check the temps if those check out then come back and we will try to help answer this question further.

ah, i remember seeing a video on this a while back, i think you're right about the pressure situation. i've also monitored my temps and they're all within 'normal' parameters. how would you suggest going about balancing fans so that it's only partially positive pressure inside? thanks for the help

https://gyazo.com/1fbcbc358fd9f79ee9b057e746f2a27f thats a quick paint of my fan config if you can understand it, it's worth noting that the exhaust on the top has a dual rad with 2 fans, but only 1 240mm case fan to vent it, if that makes any sense? (not my actual pc just same case)

 

[Codrru]

oh ok i see, if thats about the space you are working with, switch the psu to pull down from gpu it exhausts out the back, front rad fan into case, rear rad fan and rear case fan out of case. run it for a good while and see if that changes things.

 

[Codrru]

if it is not enough have both rad fans going in and just use the rear fan and psu to exhaust.

 

[deathsqaud3]

oh ok i see, if thats about the space you are working with, switch the psu to pull down from gpu it exhausts out the back, front rad fan into case, rear rad fan and rear case fan out of case. run it for a good while and see if that changes things.

Okay, thanks for your help, I shall try that tomorrow appreciate it