The video card is very hot under load, how to fix it?

Question

Iron

Let's start with the hardware:
ASUS F2A85-V PRO motherboard (latest bios)
AMD A10 5800K processor - overclocked to 4.3
CORSAIR Vengeance CMZ8GX3M2A1866C9R DDR3 memory module - 4x 4GB 1866
PSU THERMALTAKE Toughpower Grand TPG-1050MPCEU, 1050V
Case ATX AEROCOOL Mechatron
Video card MSI HD 7970 TwinFrozr III OC Boost Edition
In all PCs (wherever it is installed), the video card behaves chic, does not overheat, does not make much noise, it only starts to make wild noise and heat up under loads in my PC, it reaches 100 degrees, the protection works and the PC reboots. I changed and installed an old GTX 580, it behaves much better, but a minute passes in any load, it starts to "take off"))) and the same story. Knowledgeable people tell me what's the matter. I believe that there are great programmers here who have come across this. Thanks in advance!
On all video cards with super cooling and thermal paste, the system unit is blown from all sides and the CPU has never risen above 60 degrees. CPU idle 25 degrees. I sin on PCI due to the fact that there is no support for PCI 3.0, but it's hard to believe), or because of overclocking the mat. The board may be supplying increased voltage to the pci connector (is this possible?)

Answer 1

"In all PCs, the video card behaves chic," - which ones? what configurations?
For a second, the A10 5800 cannot fully load this graphics accelerator.

Answer 2

Cool down.
And if, in essence, the thermal paste was simply badly laid

Answer 3

Change the power supply and connect the adapters without additional power - from the power supply to the video right away. In general, the fewer connectors, the better. Make sure the wires are thick and of good quality.
It seems that the overheating is due to a lack of power.