clarry, I didn't know what ROG was but I thought it must be the brand name or something. I don't know what to tell you - I just report the facts as I see them. I looked all through the BIOS/UEFI and NOWHERE does it mention USB! I'd post a screenshot but I don't know how to do that while in the configuration settings.

osm, I agree, it shouldn't be nearly this difficult, but somehow it is! What are you laughing about?

You know maybe it calls it something else. External drive, removable drive, removable media, or the USB stick by its name or brand or or size or slot or host interface if it's plugged in. Snap a photo with your phone.

Most computers have a direct key to choose the boot device, usually f8, f9, f12 or ESC at startup.
You do the same like you go on BIOS but instead pressing f2 try f8, wich is the most common key for ASUS.

Edit: As a second option: On most ASUS boards with UEFI, you can go into BIOS/UEFI pressing f2 at startup and then press f8 to bring a boot menu.

Also I'd sure like to know which exact motherboard you've got.

Yeah mine goes in the boot menu straight from POST with F8 (and yes it is documented in the manual). Both UEFI and the boot menu identify bootable devices by their name and size: https://imgur.com/a/T0RF8fs

clarry, it doesn't really mention any drive of any sort, except hard drives. And my phone doesn't have a camera, nor would I want it to, because I hate cameras and don't want to have them around me. They're one of the biggest nuisances to privacy.

Dark_art_, mine doesn't have a key like that, or at least it doesn't mention one in the message while the computer is first booting, nor does it say anything about it in the manual. From within the UEFI however, it does have a list of things that I can boot directly from there, but the only things on it are Windows and Ubuntu (which is how it refers to the Linux installed on the HD). When I switched to BIOS mode two additional options appeared, including my DVD-RW, and also an option to "boot from the hard drive", which seems rather vague, and displayed the same ID as for booting from Windows, which seems rather redundant.

clarry, the DVD included with my motherboard says "ROG STRIX H470-I/8460-F&H", so I guess that's what you're referring to, but I'm not sure. I'll check those screens again the next time I'm there but I swear they didn't mention anything that could have referred to a USB device. But the relevant question is, if I boot from the Windows advanced startup and tell it to boot from the USB then shouldn't that theoretically have the same effect?

Seriously, why couldn't you just spit out whole name while you're at it?!?

For a programmer you certainly are very vague and unspecific about things... :D

EDIT: It was H not X.

Ok first things first.

1. Do you or do you not have access to BIOS? If you do, what do you press to get there?
I'm guessing it's DEL.
2. If you get into BIOS, have you disabled Fast startup and Secure Boot? Leave CSM enabled.
3. If you get into BIOS, have you setup USB drive as the priority?

I found some info for ASus Bios'es here but really you could find it in most places. You just need to go into the Boot tab in BIOS advanced mode and set it up.

Once the USB booting is set up from the BIOS, the next step is to install a decent distro to a correctly formatted and partitioned USB pen drive.

4. Use Live USB of whatever distro to boot into a live session
5. Use eg. Gparted in ubuntu flavours to partition a pen drive with at least the following
a) FAT32 600MB GPT with boot flag on (this will be the UEFI boot ESP partition)
b) rest unallocated

6. Start installing Mint/Ubuntu/whatever
When you get to the partitioning screen, select custom
a) boot loader in to the USB pen drive (might even have to mount to boot/efi in some cases)
b) root EXT4 with at least 8GB (not sure if enough or what size your pen drive is)
c) home EXT4 with rest of GB

So what we are doing here is ensuring first of all your rig boots from USB always if there is a bootable USB (should be the case by default in my opinion).

Then, we are putting in the UEFI bootloader into the USB pen drive. This *shouldn't* interfere with your Windows EFI or Linux GRUB (whichever bootloader you use for your dual boot), unless we are booting from the USB. After all, if you unplug the USB drive, there's no way it could interfere with it, right? To all intents and purposes it no longer exists. Much like when we are experimenting with distros and using various live linux USBs.

I'm pretty sure this should by all reckoning work and is not too difficult - in fact, I could try it out myself with my 16gb USB3 pen drive if I hadn't had so much to drink for a Halloween party and could be arsed.

Ok now that you've *finally* revealed what your board is, we can take a look at the manual and.. tada.. same as pretty much every other ASUS board. EDIT: grr sorry, nevermind, sanscript linked the wrong manual. Still, I found a screenshot of STRIX H470-I Gaming BIOS and in EZ mode it says F8 is boot menu so I'd guess that gets you there if anything will.
Honestly I have no idea. What actually boots when your system starts up is all up to your firmware first (and then whichever bootloader the firmware started up). If there is a way for Windows to tell the firmware to boot something specific, then so be it. Normally I don't ask my OS to make changes to BIOS, if I want something from my BIOS, I go in BIOS and tell it what I want.. (I don't use windows, and I haven't used windows for nearly two decades, and I'm not aware of any generic way from within linux/bsd/any other OS I use to tell the firmware to boot a specific device)

Selecting boot order will usually list the device, not partition or OS.

A modern BIOS boot order can look like this:

Sandisk 32G
Hewlett-Packard DVD-RW
Samsung 820 512
WD Green XXX

And also, any USB devices capable of booting must be present at boot (ie before starting the computer.) in order to list them in the BIOS.

sanscript, sorry but I didn't have it on hand at the time. Wow, that manual is a lot more detailed than the paper one that I have.

rojimboo, I'll reply to you in the next post because yours looks more detailed, so I'll do the other ones first so that I can focus on it...

clarry, that was the wrong manual? I'll try pressing F8, but I don't see why it doesn't say that in the message when the computer first starts.

sanscript, yes I realize that it does that, or is supposed to. It always did for my previous computer that I got in 2013, and the one before that from 2007, but this one that I got a couple of months ago won't display that information, so I guess things are just downgrading over time, evidently.

Yeah it was the wrong one. X470 vs H470. I checked the H470-I manual and it does indeed seem pretty sparse, and though it did mention a boot menu once, there was no hotkey mentioned that I could find.

Anyway, if UEFI does not show the stick in boot priority settings in advanced mode, then I doubt the boot menu would show it either (still worth a try). Sounds like "something's up" and it could be just a bug in BIOS (tried update?), but I'd first double check that fast boot is disabled and then play with the CSM settings (generally you want CSM enabled, might have to play with legacy/legacy+uefi/uefi/ignore toggles to make sure it's actually giving the device a chance at all). Designed by retards. They value "pretty" and branding over information. You remember how BIOS used to be, right? No splash screens and big logos and graphics, just raw information. Showing lots of text and information on screen at boot is old fashioned (but so nice!). Unfortunately PC bioses have never been very nice. I wish we had more open source firmware as an alternative to the crap they ship, but that is an uphill fight not worth fighting (hardware changes too fast and isn't documented well enough).

I remember the manual that with one of my first computer; two sizable manuals almost fitting for a lexicon. Then again, we didn't had internet in those days ;)

I don't know. If you've plugged it in directly into one of the USB ports in the back (either USB2, 3 or 3.1) and the pendrive is properly setup with a Linux partition and GRUB, I find it strange that it doesn't show up under Boot Option Priorities... (perhaps there is something under USB Configuration. See if USB Mass Storage is enabled (page 36))

https://www.youtube.com/watch?v=TzAHAq8VXOo

In any case, sometimes clearing the cmos (reset BIOS) might do the trick.

1. Yes I press delete to do it.
2. I've disabled Secure Boot (not manually, but it seems to have happened automatically when i installed Linux on the HD, or some time after that - I read that I shouldn't disable it because it will cause Windows to throw a fit, but it doesn't seem to have had any adverse effects). I'm pretty sure Fast Boot is also disabled, but I'm not certain. Is that the same thing that windows calls fast startup, which I think requires hybrid sleep/hibernation?
3. I can't set the USB drive as a priority because the USB drive doesn't appear anywhere. And yes I've looked all through the advanced mode.

4. That's what I've been doing with Mint, though out of curiosity, what do you think of installing with UNetbootin? At least that's what I think it's supposed to do, and run instead of the regular installer, from what I've read, but I haven't used it.
5. I've been using GParted to partition it
a) I did that except that I used 200 MB. You really think it needs 600 MB? I mean I can easily do that, and it's no problem at all, but I'm just surprised that it would need almost a whole CD worth of data just for the booting process to work.
b) I'm not supposed to make a partition with the rest and format it as ext4?

6. In the case of Mint there's an option called "something else" but I guess it's safe to assume that's what you mean by "custom" since that seems to be essentially what it does (I'm just being thorough and accurate).
a) I'm not sure what you mean by this step, but I think it's the syntax that gets me. Do you mean that I should instlal the boot loader onto the 600 MB partition that I made? I'm not sure that I'd have to mount it to boot/efi though, because I've never done that before. I just put the USB stick in and it mounts automatically - plug and play.
b/c) I wasn't planning on having a separate partition for root and home, but I could do that if it's necessary. Is it?

Right, ideally it would work similarly to how the live installer one works. But in terms of interference, it has been the other way around - the GRUB on the HD has been interfering with the GRUB on the USB and preventing it from booting. Unless you're referring to the fact that the USB installation corrupts the GRUB on the HD, but that happens only during installation and is easily repairable (though repairing it is what's been making the USB unbootable).

Well I think you might be right, and I'll try it tomorrow, after I get some other chores done which should only take a couple of hours in the morning. In any case, I wouldn't want you to be arsed... whatever that means. But thanks for the advice.

The one I linked to? If so then I'll remove it.

EDIT: Yes, I saw X where the H was.