Question Newly built gaming PC slows down entire network

Nov 28, 2020
So i have a brand new gaming pc, and its completely fresh windows install. My room has a total of 6 outlets in a single wall board and all of them have proper voltage, my electrician checked with a multimeter. My PC has a wifi antenna(magnetic) which i attached it to its metal cabinet. My router is Netgear R6850, and its placed within one meter of my pc, and my monitor is between it. My speed is 150mbps, and i acheive exactly that on the 5ghz band. Problem is, whenever i turn on the computer, it will slow down the whole network to speeds like 10-15mbps, sometimes even 1-2. It doesn't matter if the wifi is off, or even if i do a wired connection straight to the router.
On my wall outlet i have plugged in my monitor, speakers, router, modem, and the PC. When i took my PC to another room, the speeds were great, as they were supposed to be. But the problem is only in my room. My electrician says it cannot be a problem with my outlets, as they are supplying adequate voltage. My ISP is puzzled.