Connected Standby relies on a set of relatively new power states known as S0ix (active idle). This is explained extensively over at AnandTech, in their introduction to Intel's Haswell architecture:
The solution is connected standby or active idle, a feature supported both by Haswell and Clovertrail as well as all of the currently shipping ARM based smartphones and tablets. Today, transitioning into S3 sleep is initiated by closing the lid on your notebook or telling the OS to go to sleep. In Haswell (and Clovertrail), Intel introduced a new S0ix active idle state (there are multiple active idle states, e.g. S0i1, S0i3). These states promise to deliver the same power consumption as S3 sleep, but with a quick enough wake up time to get back into full S0 should you need to do something with your device.
Haswell represents the 4th generation of Core iX processors, and Clover Trail is the Atom Z27x0 series. Moving forward, I think it's safe to say that post-Haswell and post-Clover Trail processors (including Broadwell and Bay Trail as of time of writing) do have S0ix support moving forward.
Now, processor support is not the only obstacle. There are many other stringent requirements for Connected Standby to be enabled, most notably:
- Platform-level support (ACPI firmware), this requires the firmware to be marked as explicitly supporting Connected Standby
- NDIS 6.3 support in built-in networking devices
- The primary volume must be solid-state (i.e. flash/SSD)
- Secure Boot to be enabled
- RAM to be soldered onto the motherboard
In summary, there are a lot of requirements to be met before Connected Standby is enabled. If the device is a tablet and is pre-loaded with Windows 8/8.1, chances are, it likely does have Connected Standby enabled.
If you're looking to disable Connected Standby on a Windows 8/8.1 tablet, you can change the registry setting at
HKLM\System\CurrentControlSet\Control\Power\CsEnabled from 1 to 0 (more information here).