Power Surge Killed My PC’s PSU But It Also Won’t Boot Without GPU — What’s Going On?

Last night there was a sudden power surge at my place, and it fried the power supply unit (PSU) in my custom desktop. I replaced the PSU with a new one of the same wattage and brand, but now the PC won’t boot unless the GPU is installed. Before the surge, I could run with integrated graphics just fine since my CPU supports it. I double-checked all connections, reseated the CPU and RAM, and even reset CMOS to clear any BIOS hiccups. The motherboard powers on (LEDs light up), fans spin, but no POST beeps or display output without the GPU. Plugging in the GPU brings everything back to normal. Is it possible the power surge damaged the integrated graphics on the CPU or some motherboard circuitry? Or maybe the BIOS got corrupted in a way that disables integrated video? Has anyone seen something like this? What would you test next to isolate if it’s the CPU, motherboard, or just a weird PSU compatibility issue? Any creative troubleshooting ideas appreciated!