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It’s very slow and pinwheels on every task, even just opening system preferences. I checked the cpu usage and it is pretty much pinned at 93% kernal_task being the cause. Anyone have an idea of what could be causing this? I’ve tried smc and pram clearing. MacOS reinstallation. I’ve also bought seagate firecuda sshd and cloned my oem hdd and installed that with no change in performance.
First I don’t recommend cloning. In days past it was a very useful method but todays OS’s it tends to mess things up. In addition when you have SATA cable breakdown which I suspect it your issue here any errors on your original drive will past over to your new drive. Follow this IFIXIT guide to replace the HD SATA cable: MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement and here’s the cable you’ll need: MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable. In addition you’ll want to put down some electricians tape on the uppercase where the cable rests. Once you have the cable installed you’ll need to wipe the drive down and re-install the partition and format it. Using either internet recovery or if you have a bootable OS installer USB thumb drive (the faster method). Once your drive is up and running use Apple’s Migration Assistant to copy over your stuff References: How to create a bootable macOS Sierra installer driveStartup key combinations for MacHow to move your content to a new Mac
