(get his crayons out)
i've tried, and hinted, but I'm now going to say it
64bit windows wont run on your 64bit tablet.
Your Z series baytrail wonder of engineering only has a 32bit compatible UEFi (call it a bios if you feel better about it)
Your cpu is 64bit, awesome. Yet 64bit code wont boot. You get some shims and stuff you can use to help boot ubuntu and android, after a ****load of faffing, but without a "bios upgrade " (in quotations, coz it isnt a bios, its uefi) from the manutfacturer all you will do is look at your 64bit installation disc. You cant use it. End of discussion. And the manufacturers?Unless it is a tier 1, well, they made a thing and it worked and you bought it, now stoip bothering them for a 64bit uefi, they dont know how to make it.
And now, why is this? wot 'appened?
Intel+MS were rushing like buggers to get a cut price tablet out to counter the android surge, and Microsoft wanted connected standby (sleep mode, but with wifi on, so your email make a "ping" sound etc even when in standby) and that only worked properly on a 32bit uefi at the time, so that was the combo that shipped.
If you have a baytrail, Z series cpu, with windows 8.1+bing (from a grey-ish manufacturer) , 99.99999999999999999% it is always true that you have a 32bit uefi and are stuck on 32bit windows.
and those that want to upgrade your memory...from the instantgo/connected standby wiki page
"It requires the following:
A firmware flag indicating support for the standard
The boot volume must not use a rotational disk
Support for NDIS 6.30 by all network devices
Passive cooling on standby
There are additional security-specific requirements, for example for memory to be soldered to the motherboard to prevent cold boot attack vectors that involve removing memory from the machine, as well as support for Secure Boot.
On Windows 8.1, supporting InstantGo and having a Trusted Platform Module (TPM) 2.0 chip will allow the device to use a passive device encryption system.[4][5]
Limitations
Systems that support this specification are incapable of booting legacy BIOS operating systems.[6] PCs with Connected Standby also cannot manually enter the Sleep and Hibernate power states."
You are unable to set the thing to bios mode, you are unable to load a 64bit uefi...you are stuck stuck stuck on 32bit windows.
https://wiki.archlinux.org/index.php/HCL/Firmwares/UEFI#Intel_Atom_SoC_Bay_Trail
bottom of page re: baytrail