I have a USB HDD that I'm hoping to install Windows on for a few games and other pieces of software. I know my load times will be miserable, but how poorly will things run once on ram? Lastly, Windows does like to screw with other operating systems on the same drive, will it play nice with my main drive as long as it's on the HDD?
They'd be very miserable. Also I've heard that Windows likes monopolizing your boot partition when installing by default but mechanically I think you can do it with enough diligence and after backing up your important stuffs.
But honestly, my advice is to look into running Windows using Linux KVM+QEMU (through a front-end like virt-manager). If your system is too weak to virtualize Windows then I doubt you'd get any luck running windows on a USB HDD if the goal is to just run certain games and programs.
I have a VM that works for some things, but performance is too slow for games or CAD and some software cannot run on a VM at all. I might see if I can set up GPU passthrough but I don't want to deal with that hassle because I've heard it's a pain.
It's not worth it if you have a single GPU (at that point just dual boot like you're planning to now), but if you have a second GPU then it's a very powerful option.
You can always bite the bullet and have Windows and Linux be neighbors on the same drive though only Linux is chad enough to read from both OS's partitions. If your concern is with performance then I don't think Windows would be good at all on an external HDD.
Yep, seen this happen a couple of times with friends. Their boot loaders just randomly get nuked from their EFI partition after a Windows update,
You can pass through a single GPU, it's just kind of a pain to get working so I wouldn't really recommend you bother with it unless you really want to go this route. Another option is to pick up some ancient very cheap graphics card up off Ebay or something to use for the host machine then pass through your more powerful GPU to the guest machine.
This is a laptop so could I use the igpu for the host that already runs the UI and pass the GPU through to the VM?
Looking it up supposedly theoretically possible but I think the CPU has to support it https://www.reddit.com/r/VFIO/comments/xpjihb/guide_gpu_passthrough_for_laptops_in_fedora/
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Thats where I get half of my garbage from.