Strange smell from my PC when my GTX 970 temperature reaches 70° C

[Krigga]

What can this smell be? Is it hot dust or maybe my cables which lay like that:

What you can you see above the card is not smoke, its unclear glass of my PC.

 

[DSzymborski]

You're going to have to try to get in there yourself and start sniffing when it happens as a blurry, dark, closeup of a tangled mess of rather cheap-looking cables isn't much of a clue in itself. Full specs too - all I know is that there's a smell and you possibly have a garbage PSU, but nothing more.

 

[Krigga]

PSU is Aerocool VX-600
Graphics card is MSI GTX 970
Motherboard is MSI H110M Pro-vh
Processor - intel core i5 6500
Processor cooler is some Deepcool

 

[turkey3_scratch]

Aerocool is known for anything but good power supplies. The most common thing to burn are the connectors. The connectors are not the wires themselves but the thing at the end of the wire that plugs into something else.

I would unplug your PCIe cables from the GPU and inspect those with a flashlight for burn marks. I'm talking about the silver things you see in the little holes:

 

[Karadjgne]

70°C is hot by any standard. Easy when wiring comes on 75/90/105°C insulation. And you have those wires, and looks like zip ties, sitting on top of the heatpipes. Your pc has been this way for a while, good chance of the heat getting to that wiring and drying it out, causing it to brown, possibly melt. That's not to mention any possible damage caused by wiring bundles sticking into fans, preventing rotation, and burning up fan motors.
Unplug the pc, open the side door and fix the wiring nice and neat, away from heat sources. It's a mess as is. Make sure to inspect everything possible for melting, discoloration etc.

Oh,if you are worried that the smell could be caused by old, dried out dust etc, then you obviously do not clean the pc thoroughly enough or frequently enough. Just saying.