DXPower

I recently moved across the state, so I transported my computer as normal: put the graphics card in a separate box and reassemble it at home. However, I tried playing Planet Coaster when I got home, and I was struggling to get 20fps minimum-settings in an empty map (I normally get 30-40 on ultra on a medium-sized park). I did a lot of troubleshooting at this point. I tried resetting all the game's settings to default, I tried forcing the game to run off the 970, I disabled/enabled various settings in the control panel. Nothing seemed to work. I tried loading up another game, that ran fine for some reason (Doom on high-ultra at 100+). Eventually I got MSI Afterburner and I tried setting up OC to see if it got tuned down for some reason. Didn't work. Then I noticed that my GPU was constantly pegged at 100% in the game, even at minimum settings. After some searching, I figured I should check the slot my card is plugged into. As it should have been, it was in the x16 slot. Finally, after more hints from a few forums, I downloaded GPU-Z and used their PCI speed test. There, I found the culrpit: My card was running at PCIx2 instead of x16. I looked inside my case and noticed that my one of the two CPU power cables had come out of the slot. My questions to the hardware experts here: how the hell did my computer even boot at all with 1/2 of the CPU 4-pins plugged in? Why did this not affect CPU performance at all, but rather affected the performance of the GPU (as in, the speed of the PCI slot)? Why did I only see this issue in Planet Coaster, and Doom ran perfectly fine? Relevant specs CPU: i5-4690K (No OC) GPU: MSI 970 PSU: EVGA 850 B3 Motherboard: Gigabyte GA-Z97X-GAMING 5 I'm mostly posting this for posterity in case anyone else runs into this problem again. But, I also want to know the technical reason as to why I saw the behavior I did.