Laptop waking up from sleep because of "power button"? (Windows 8.1)

My computer is brand new but has a serious problem - it wakes up from sleep mode on its own in the middle of the night, usually a couple hours after I put it into sleep mode. This problem is consistent and I have been sure that I really put it into sleep mode before putting it away. No peripherals are attached to the computer when this happens.

I have already checked for what is waking it up consistently in Event Viewer using the instructions here. It's not a program or device. It says it is the "power button"! From the event viewer log:

The system has returned from a low power state.

Sleep Time: ‎2015‎-‎07‎-‎02T03:44:42.484673200Z
Wake Time: ‎2015‎-‎07‎-‎02T06:44:45.019268100Z

Wake Source: Power Button

powercfg -lastwake also gives the same "Power Button" as the culprit every time I run it after finding my computer running hot in its case after supposedly sleeping.

I checked the power management settings and all wake timers are disabled, and from the command line I checked and no devices are allowed to wake the computer up (used powercfg -devicequery wake_armed command) and no wake timers (used `powercfg -waketimers command). I manually checked my wireless card too, it does not have wake privileges. Automatic maintenance also does not have the ability to wake up the computer (the box is not checked).

Windows Update also doesn't appear to be the culprit - it hasn't installed updates for over a week, and this problem has continued throughout. I tried disabling automatic updating just to see if that works.

The computer is closed and sitting on my desk. There is no way I am touching the power button in the middle of the night! This happens every night that I put the computer to sleep.

System specs:` ASUS UX305FA (Core M 1.0Ghz, 8GB RAM, 256GB SSD), brand new

Running Windows 8.1 and updating regularly

Installed programs: Microsoft Office 2013, Skype, Adobe Lightroom 3.0, Dropbox, SMPlayer, Firefox, Chrome, CutePDFWriter (the problem has been pretty consistent since I bought it so I really doubt its software).

Antivirus: Sophos

I've looked at every forum post I could find to no avail. I also contacted ASUS and they said this is not a common problem, and indeed I haven't read anything about it being common with this computer.

I was having this exact same problem on my custom PC build. After entering sleep mode my computer would wake up, seemingly on its own, after a random amount of time. Sometimes it would stay asleep for hours and sometimes it would only stay asleep for a couple minutes.

I had already tried disabling the option of "Allow wake timers".

The Event Viewer and powercfg lastwake were both reporting that the "Power Button" was the cause of my computer resuming from sleep mode. After some reading of various forum and blog posts, it was suggested to try disabling "Wake On LAN" on my network card.

I followed this guide on how to do it:

• open Device Manager
• right-click on your Network Adapter, open Properties
• go to the Power Management tab
• uncheck the "Allow this device to wake the computer" option
  • alternatively, you can check the "Only allow a magic packet ..." option

I haven't experience another sudden awakening since I disabled this "feature".

Go to:

power options/change plan settings/change advanced power settings/sleep/allow wake timers

Then check disable to both "on battery" and "plugged in".

Click OK and close the window. Enjoy your night's sleep!

I had this exact issue with my Asus G551JW laptop, same /lastwake results and everything. Updating the BIOS to the latest build solved my problem, but I do not know if yours is up-to-date or not.