I would recommend just booting a Linux USB stick, then running gdisk in there to convert all of your data drives to GPT without changing the way in which they're connected.
My Current C:\ drive is only 500GB so no point to make it GPT
Using GPT is not entirely about the disk size. Among other things, it is usually a requirement for booting Windows in UEFI mode.
(Though not necessarily for booting an OS in UEFI mode in general.)
i don't see any UEFI mode thing in the BIOS but it is UEFI capable according to the motherboard manufacturer. i could test GPT as said
The labels for this vary depending on manufacturer and the firmware's age. It might be "BIOS compatibility" or "legacy mode" or "CSM mode". Often, UEFI firmwares work in hybrid mode where the same boot menu offers both BIOS-mode and UEFI-mode options, so they might not necessarily have a global switch for that.
The boot mode, however, has nothing to do at all with your data disks. Those are read only by the OS – not by the firmware – and they can use any partitioning (or lack thereof) that the OS will support. All recent versions of Windows (post-XP) will be able to access GPT and MBR partitioned disks on any platform.
using Disk Management i discovered that i can only convert to GPT
when no partitions and data are present (tested with an old 160gb hdd with sata to usb cable). which means converting MBR to GPT after
There are other partitioning tools besides the Windows Disk Management applet which can convert a disk with partitions from MBR to GPT and back – the Linux gdisk being one example. This process doesn't do anything with your data; it just writes the same partition start/end information to the new table.
would it work to hook up a new 4tb ssd using sata>usb cable, convert it to GPT using Disk Management, then clone it?
Probably not. If you clone the whole disk, this will just overwrite everything that's on the destination disk – including your freshly prepared GPT partition table. (It is stored on regular data sectors – specifically, sector 0 for the MBR and sectors 1-33 for the GPT.)
But also, be careful with SATA-to-USB adapters. Some of them emulate a different sector size for the disk – a '512b' disk connected through some such adapters will be seen as if it were a '4K' disk, that is, with virtual 4096-byte sectors. If you create a GPT partition table through such adapters, it will not be recognized when the same disk is connected directly, nor the other way around.
(This is actually considered a "feature" – it's meant precisely to allow MBR usage on disks larger than 2 TiB, as the limit comes from the number of sectors, not of bytes.)
is cloning better with software (clonezilla/acronic true image, etc. on bootable usb) or hardware? i cloned my C:\ recently with one of those Sharkoon boxes and it worked perfectly. however, i didn't bother with MBR- GPT since i went from 120GB > 500GB, and MBR tops out on 2TB
In theory, software might be more flexible – e.g. it might support cloning individual partitions from a MBR disk to an already-GPT disk; or if you are cloning a typical Windows system to a larger disk, it might support automatically growing the C:\ partition to the new size, and even shifting that pesky "Recovery partition" so that it ends up at the very end of the larger disk, instead of somewhere in the middle. (This is a theory. I haven't used cloning software which would do this.)
But when cloning the entire disk 1:1, it doesn't make any difference how you do it.
does cloning itself affect the partition table?
As mentioned, it may or may not affect the partition table – it depends on how the cloning software actually works. If it clones the entire disk as a unit (like hardware cloning devices would), the output will have exactly the same partition table as the input, too. But if the software wants to be flexible (e.g. if it has options to clone only selected partitions but not others), then it is likely that it'll build a new partition table... though usually of the same type anyway.
