The space is on the disk — it is just in the wrong partition. NHV Boot carries three professional partition managers that can shrink D and grow C without reinstalling Windows or losing data. Done in the right order, with one backup habit observed, it is one of the safest big operations in PC repair.
C drive is full" with 200 GB sitting free on D: is one of the most common — and most unnecessarily feared — jobs in IT support. Windows' own Disk Management often refuses to help, because it can only extend a partition into free space directly beside it. The partition tools inside NHV Boot — MiniTool Partition Wizard, AOMEI Partition Assistant, DiskGenius and EaseUS Partition Master — are not bound by that limit, and running them from WinPE means the system partition is offline and fully movable. This page covers the full job: the honest risk statement first, then health and BitLocker checks, then the resize itself.
Modern partition tools are designed to resize without data loss, and in normal conditions they do — millions of times over. But "designed to" is not "guaranteed to". A power cut, a forced shutdown or a failing drive in the middle of moving data can corrupt the partition being moved. So the professional rule is absolute: back up first. NHV Boot makes this easy because the imaging tools ride along — take a system image with Macrium Reflect or AOMEI Backupper onto an external drive before you touch the layout. With an image behind you, resizing stops being a gamble and becomes a routine job with a rollback.
Open CrystalDiskInfo and read the SMART status. Resizing a drive that reports Caution or Bad is asking a sick disk to do heavy lifting — replace the drive (cloning it with the same toolkit) instead of rearranging it. Next, check BitLocker: if the system partition is BitLocker-encrypted, most partition operations require it to be turned off and fully decrypted first, because the tool must rewrite structures the encryption layer protects. Unlocking alone is not enough for a resize. Start the decryption from inside Windows, wait for it to reach 100%, and only then boot NHV Boot.
Open your partition tool of choice — the steps below are written for MiniTool Partition Wizard and translate almost word for word to AOMEI and DiskGenius:
Position is the whole game. Free space anywhere else on the disk cannot extend C: — if your layout forces it, the tools can also move a partition, which is slower but equally supported.
Now select C:, choose Move/Resize, and drag its right edge to absorb the unallocated space. Review the pending operations list — shrink, any move, extend, in that order — then click Apply. From this moment the rules are simple: laptop on its charger, no interruptions, no "just checking" reboots. Extending alone is fast; moving a partition's data is the slow part and can take from minutes to over an hour on a mechanical drive. The tool reports each operation as it completes. When it finishes, reboot into Windows normally.
Windows will usually boot as if nothing happened, with a bigger C:. Do three quick verifications: open Disk Management and confirm the new sizes, run chkdsk C: /scan from an administrator Command Prompt as a sanity check, and open a few files from D: to confirm the donor partition is healthy. Only then, if you decrypted BitLocker for the job, turn it back on — a surprising number of machines stay unencrypted forever simply because nobody closed this loop. Finally, delete the pre-resize backup image only after a few days of normal use, not on the spot.
Editions, USB creation, first boot and the full tool tour — everything in this guide, shown live on real machines.
▶️ Watch Full VideoDisk Management can only extend a partition into unallocated space directly to its right, and it cannot move partitions at all. The tools in NHV Boot can shrink, move and extend, and they run offline — which is why technicians do this job from WinPE.
Extending into adjacent free space: a few minutes. Moving a partition that holds hundreds of GB: potentially over an hour on an HDD, much less on an SSD. The tool shows progress per operation — plan the job when the machine is not needed.
Almost always position: the unallocated space is not immediately next to the partition you are extending. Shrink the donor from the edge touching your target partition, or use the tool's Move function to slide the free space into place first.