It's terrible. I remember being woken up one night because my laptop decided to wake up and resume the Netflix video I'd be watching earlier. No input devices connected, lid closed. Another time it cooked in my bag because windows wanted to do an update on shut down so I slept it instead.

I have a 2017 XPS model so I the firmware supports S3 sleep. There is no modal in the BIOS though. I had to trick windows into thinking it didn't support modern sleep.

Based on posts from others trying to do the same thing, it used to be a single registery key edit. Now it's convoluted and required fiddling with WiFi power controls. The end result it sleeps properly but takes anywhere from 10 seconds (good) to more than a minute (bad) to connect to WiFi when woken up.

Of course on Linux it just works.

Back when I was looking into this I found someone who'd found a way to patch the acpi table to enable it for the newer models (at risk of bricking the device entirely). Alas I can't find the link any more.

I won't buy another Dell until this is fixed.

My work laptop is an X1 carbon and it supports only S3 sleep so it just works.

> Switching the power model is not supported in Windows without a complete OS re-install

That's absolutely insane.

Spoiler: I have an XPS 9500 under Linux, which sleeps fine under S3 but then it never wakes up. So the problem isn't with Windows.

So you’re actually "putting it to sleep", when you put it to sleep.

What does "never wakes up" mean? I thought I had the same problem but then I discovered that closing and opening the lid is the only way to get it to wake. Neither the power button (it turns it off) nor keypresses (they do nothing) work.

I think I tried everything, from buttons to lid to magic network packets. Once in S3 it's dead Jim, and there's nothing in the BIOS to change that behavior.

The irony is that I have a 4 years old XPS 13 where everything works like a charm, even under Linux. Talk about progress ...

I’ve had a problem like this with my XPS and I was able to solve it by holding the power button for 25-40 seconds to reset something:

https://www.dell.com/support/kbdoc/en-us/000125880/how-to-re...

A comment above mentions manufacturers removing S3 support from their bios with the exact symptoms you mentioned

I have an XPS 9500 and it sleeps+wakes, as expected, with S3.

Intel just removed S3 sleep completely from the latest Tigerlake chips.

I don't think it's the OEMs / manufacturers, it's Intel.

Seems to be mostly a Dell/Microsoft problem, haven't heard of other vendors removing S3 functionality (yet, anyway).

I've got a Lenovo Yoga Slim 7 which doesn't advertise S3. It's a really nice machine, but having to wait several months after getting it for someone out there who understands these things to come up with the right combination of kernel code and ACPI patches so I could shut the lid and not have it just reset when I opened it back up again was something I could have done without. Fortunately it's got the capability, it just needed turning on.

hi i have the Yoga Slim 7 too (the white carbon fiber one). How do you enable this ?

The DSDT mod at https://github.com/jrandiny/yoga-slim7-ubuntu worked for me to stop it resetting, but only on the 5.14 kernel. YMMV.

ASUS UM325

Weird, I got a newer Asus (Flow X13) and it does S3 just fine.