Random Shutdowns - Kernel Panic - iMac 2013 27'

panic(cpu 3 caller 0xffffff7f8d864e82): NVRM[0/1:0:0]: Read Error 0x00070000: CFG 0xffffffff 0xffffffff 0xffffffff, BAR0 0xb0000000 0xffffffa3c195b000 0x0e7200a2, D0, P2/4

Kernel Extensions in backtrace:
 com.apple.nvidia.driver.NVDAResman
    dependency: com.apple.iokit.IOPCIFamily
    dependency: com.apple.iokit.IONDRVSupport
    dependency: com.apple.iokit.IOGraphicsFamily
    dependency: com.apple.AppleGraphicsDeviceControl
 com.apple.nvidia.driver.NVDAGK100Hal
    dependency: com.apple.nvidia.driver.NVDAResman
    dependency: com.apple.iokit.IOPCIFamily
 com.apple.GeForce
    dependency: com.apple.iokit.IOPCIFamily
    dependency: com.apple.iokit.IONDRVSupport
    dependency: com.apple.nvidia.driver.NVDAResman
    dependency: com.apple.iokit.IOGraphicsFamily
    dependency: com.apple.iokit.IOAcceleratorFamily2

I would guess that your GPU is failing.

Try gSwitch to disable the discrete GPU and use the intel integrated GPU instead

gSwitch (macOS 10.12 or newer)

https://codyschrank.github.io/gSwitch

gSwitch lets you set which graphics card your macbook pro can use, mainly to prevent it from using the discrete graphics card

See if that stops the panics. If it does, then you know it is the GPU, and you can decide if you are going to try to have the motherboard replaced, live with it running off the intel integrated GPU, or replace the Mac.

If the panics still continue after you have gSwitch force the use of the intel integrated GPU, then, my guess is wrong.

The apps tend to work on any Mac, it was just originally written for MacBook Pros, but iMacs also have integrated intel GPUs and discrete GPUs.

The alternate is to schedule an appointment to have your Mac repaired, or consider a replacement.

If gfxCardStatus works, then you will at least have a way to know that it is definitely the discrete GPU. And if it is the discrete GPU and gfxCardStatus works, then you can continue using your iMac only using the integrated intel GPU, which while slower, would avoid an expensive repair or replacement.

That is a bummer, gSwitch not working on your Mac.

You could try gfxCardStatus

gfxCardStatus is a free menu bar application that keeps track of which graphics card your MacBook Pro is using at any given time.

https://discussions.apple.com/message/32581726#32581726

https://gfx.io

I do not know of any others. They could be out there, but I have not stumbled across them.

You can try running the Apple hardware diagnostics, but they are not all that ridged

https://support.apple.com/en-us/HT202731

Go for the internet downloaded versions, as they should be the most up-to-date.

Otherwise, take it into Apple (or an authorized service center) to see if they can diagnose and repair.

This is the same panic, which is still in the graphics drivers. So you are getting consistent panics, which helps eliminate random motherboard or memory issues.