Can I install a Windows 10 on the microSD card?

[Testudo]

So that I can still run SteamOS on steam deck. When I want to use windows, I just put the sd card into the steam deck.

[retrogunner]

unlikely. Just because an SD Card shows up as storage, it is not a storage type appearing as fixed (vs. removable) storage.

You could likely get away with installing Windows to a USB HDD/SSD/NVMe. Then on boot, select your boot device. You'd have to do this every time you'd want Windows.

You supposedly cannot have SteamOS dual boot using its bootloader as it's a custom one written specifically for SteamOS with its boot recovery in mind.

[Silence]

There are some ways but you need a bit of technical knowledge. you can install windows on the device, setup everything and then move it to a virtual harddrive (vhd(x)). Next, you install ventroy[www.ventoy.net] to your microsd card with support for the virtual harddrives. then you can copy your vhd to the microsd and setup the boot entry for it.
if you now enter the bios from the deck, you should be able to boot from the microsd card. it launches ventroy that then can boot the windows on it.

NOTE: THIS IS ALL THEORETICAL!

[TheBlackDude]

idk

[Ohhnoo]

No, not at the moment (save for the possible option some kind poster has suggested above, with virtual machines, but I'm unsure if the GPU passthrough would work, but it might), and possibly the external booty drive, but I don't know how Valve's custom BIOS treats and external boot device. Does it even recognise external boot drives?)???

You're looking to dual boot, and that's an option that Valve says will appear later, and be added in BIOS via a firmware update - when available. Valve has (unhelpfully) given no ETA for the arrival of that planned update, so next week or next month, or whenever...

That said, you would have a better experience (I reckon) with Windows 11, as its better coded for touch screens and mobile devices. There are TPM requirements for Windows 11 that the Deck doesn't yet meet - and that will arrive via the same, or possibly later additional firmware upgrade (Valve really needs to improve its coms here, and its not a good customer experience to be left out in the cold). But...

There are ways to avoid the TPM requirement and install Windows 11 anyway, which is what I plan on doing... If you're comfortable creating bootable media via Rufus, then there is an option in that software to by-pass TPM and that will enable Windows 11 to install just fine and dandy... Other work-arounds exist too, (but for some options you might need to install Windows 10, then upgrade to 11) search:

"How to Bypass Windows 11's TPM"

from your favourite browser, and that should give you a number of options from more trusted web-sites...

That's what I'm doing, (via Rufus) though I will have to wipe Steam OS off the device to install Windows to the primary drive, (which I'm looking forward to doing, - if for no other reason than to hack off the Linux fascists who have taken the Steam Deck as some kind of gift from God and think it heresy to even consider Windows), but I also am left hoping that the Windows 10 drivers are not coded so that they refuse to install on Windows 11... Or I'm back on Linux (Valve have helpfully provided recovery software to reinstall Linux and restore your device if push comes to shove)... and then will try Windows 10, only if I can't get 11 to install (with drivers).

Fingers crossed!

[THFourteen]

Yes you can. I have installed windows 11 to a microsd card using Rufus. it was easier than i expected.

[AD]

Originally posted by Testudo:

So that I can still run SteamOS on steam deck. When I want to use windows, I just put the sd card into the steam deck.

I have seen someone do it on youtube, so unless they faked it, it's possible. I suggest try it. Worst case scenario it won't boot.

[TheNickster99]

You can, but if I'm being honest its a massive pain in the ass because the read/write speeds aren't sustainable at all so the OS just starts to throttle and run like crap after about 10 minutes. I tried it with a 512 GB Samsung EVO and I ultimately dropped it after a few days, games like CoD or Fortnite would stutter and have severe latency spikes because the SD card just would not cut it. I switched to an external SSD and performance is noticeably better, ESPECIALLY when directly connected from usb-c to the deck.
We are talking from 40MB/s to 1000MB/s (as I have a samsung T7).
I wish Valve would just release the dual boot wizard officially so I can just have SteamOS and Windows on the internal NVME SSD at the same time without this external storage stuff though. Its still a PITA not being able to charge the deck without turning it off and connecting it to a USB-C hub on an external Windows device.