Videocard crash problem

In general, the essence is this: there is a gigabyte radik r9 270 and periodically in games it turns off, everything hangs, the screen also goes out, and the inscription "Check the cable" appears. I sin on the power supply unit (Chiftec CHP-500A), it gives out 18A on the 12V line, and the card seems to need 24A. I ask knowledgeable people to explain. The temperature, if anything, does not rise above 60.