Computer slow/laggy/glitchy right after new PSU install

Hey guys, heres my specs:

Operating System - Windows 10 Education 64-bit

CPU - Intel Core i7 7700K @ 4.20GHz 91 °F Kaby Lake 14nm Technology

RAM - 64.0GB Dual-Channel Unknown @ 1499MHz 16-18-18-38

Motherboard - Gigabyte Technology Co. Ltd. Z270X-Gaming 5 (U3E1) 81 °F

Graphics - 24GM77 (1920x1080@144Hz) ASUS VP247 (1920x1080@59Hz)

16368 MB ATI AMD Radeon VII (ATI) 88 °F

Storage - 447GB SATA SSD (SATA (SSD)) 92 °F

74GB Seagate ST3808110AS (SATA ) 83 °F

111GB Corsair Force LS SSD (SATA (SSD)) 87 °F

372GB Western Digital WD 4000BEV External USB Device (USB (SATA) (SSD)) 92 °F

Optical Drives - No optical disk drives detected

Audio - SteelSeries Arctis 5 Game

Anyways, i have been rebuilding my computer now for the past few weeks... every so often something will arrive from newegg and ill install it. I recently ordered a new Radeon VII, an EVGA 1000w Gold, and 4 x 16 gb tridentZ ram. I initially ordered the new psu, because i had the other one for a couple years, and i wanted to add on a cpu liquid cooling system in the future, along with overclocking my cpu and gpu. I installed the ram and the gpu a week or two ago when they arrived, and i knew it would be fine because the psu i had was still a 850w gold. There were no issues with my setup, until today, when i replaced the psu. Replaced all the connections, wires, i made sure all connections are secure and tight. my friend started the pc back up, and updated my graphics drivers immediately, as he noticed there was an update. After the graphics drivers were updated, i told him to hop into a game of apex so he could see how well it was now running with the new setup. To my surprise, it was glitchy, slow and occasionally almost "slow-mo". We re-booted, the pc booted slower, auto-start programs booted slower, my mouse would literally glitch around and lag around at my desktop as the computer was starting, which has never happened. We rolled-back the drivers, assuming AMD had messed up badly, and it was still occuring. And still is now. I'm planning on replacing the brand new psu, with my old one, just to clear its name, though im sure it isnt the culprit and this is some awful coincidence. If i clear the PSU as the culprit i plan on doing a full reformat, clean install. My last option before i do those things was to come here and see if anyone had ANY idea as to why my rig is now behaving like this. My pc shouldnt be laggy and glitchy on my desktop. Btw, i have an odd hard-drive setup. 2 SSD's, 1 removable, and 1 older hdd. For some reason even though one of the SSD's has windows on it, the older hdd still needs to be #1 in the boot priority for windows to boot. So i was thinking maybe one of my hard drives is taking a **** or something, idk... i appreciate any and all insight.

Thanks

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P.S. After we installed the psu, he booted it. I wasn't paying attention and he couldnt remember if it seemed as slow as i am reporting to you now, and if it was glitchy or not. I feel like he would have mentioned it if so, but i cannot confirm that it was slow/glitchy/laggy before the gpu driver update, but still after the new psu installation.

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EDIT: I remembered i replaced a SATA cable when we were wire-tucking. I put the old one back hoping it was a faulty cable, with no luck.