Weird power flickering

Howdy all, I have a weird power issue happening in the house that I am renting. I have a computer plugged into an outlet in an office. For some reason, after 30-60 minutes, the lights all over the house begin to flash continuously. I have tried 2 different power supplies, both do the same thing. I have also tried plugging the computer into a different circuit in the house, no flashing. I have used a different power cable for the power supply, and tried three different outlets in the office, all caused flickering power throughout the house. While the flashing is happening, the mains input from the city is jumping around, I see 80-90V on one input of the 100A breaker and 130-140V on the other side. I have narrowed it down to the computer, but very strangely, when the lights begin to flicker, if I turn on a high power appliance (microwave/vacuum/even stress test the GPU to 450W) the flickering stops. The voltage in the office will stabilize and everything is fine for 60-90 seconds (not minutes), then the flickering begins again. The two power supplies are Corsair, 750W and 1200W.