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ManualGPUNVIDIA TENSOR UNLOCK
GPU · NVIDIA RTX 40

NVIDIA TENSOR UNLOCK

What it is. A one-time procedure for desktop GeForce RTX 4000 (Ada) cards that removes the GeForce half-rate limit on tensor-core math with FP32 accumulation, with FP16, BF16 or FP8 inputs. It runs from a USB flash drive before Windows starts; HYDRA prepares the drive and restarts the PC for you.

Why use it. These operations then run at full speed, twice the stock rate. That speeds up work that relies on this math, such as training and running AI models in mixed precision.

Works with desktop GeForce RTX 4000 Switch SETTINGS → GPU Safety System Unlocks FP16 · BF16 · FP8 with FP32 accumulation Needs a FAT32 USB flash drive Updated 30 Oct 2026

What it unlocks

A tensor-core operation multiplies matrices in one format and adds the results up (accumulates) in the same or a wider one. On a stock GeForce RTX 4000, accumulating in FP32 runs at half the speed of accumulating in FP16. Tensor Unlock lifts that limit:

InputsAccumulationStock GeForceAfter Tensor Unlock
FP16FP16Full rateFull rate (unchanged)
FP16FP32Half rateFull rate
BF16FP32Half rateFull rate
FP8 (E4M3, E5M2)FP32Half rateFull rate

It matters for work that runs tensor-core math with FP32 accumulation, such as AI training and inference in mixed precision. On an unlocked RTX 4080, FP16 and BF16 with FP32 accumulation reach about 212 TFLOP/s, the same as FP16 with FP16 accumulation, and FP8 with FP32 accumulation reaches about 424 TFLOP/s.

Before you start

  • A desktop GeForce RTX 4000 card. RTX 5000 cards are not supported.
  • Secure Boot off in BIOS/UEFI. The unlock program is not signed and cannot run with Secure Boot on.
  • BitLocker suspended on the system drive. Otherwise Windows stops at the recovery key screen after the unlock boot, and HYDRA does not start Tensor Unlock while protection is on. In a terminal opened as administrator: 
    manage-bde -protectors -disable C: -RebootCount 0
    A plain suspension without -RebootCount 0 ends on the very next Windows start, which is the unlock boot. Turn protection back on only after a later normal Windows start: 
    manage-bde -protectors -enable C:
  • A USB flash drive formatted as FAT32 (GPT or MBR). HYDRA does not format it: it adds or replaces only its own package files and backs up replaced files on the PC. Keep your own copy of important files on the drive anyway. Internal disks are not offered.
  • Save your work. Windows restarts 60 seconds after the drive is ready and closes the remaining applications.

Run it

HYDRA SETTINGS tab. The GPU Safety System panel holds the NVIDIA Tensor unlock switch.
SETTINGS tab, GPU Safety System panel. Click the screenshot to see it full size.
  1. 1SETTINGS. The gear icon in the top-right corner of HYDRA opens this tab.
  2. 2NVIDIA Tensor unlock. The switch in the GPU Safety System panel.
  1. Switch NVIDIA Tensor unlock on.
  2. If the PC has more than one RTX 4000, choose the current card or all of them. The cards are processed one at a time.
  3. Choose the FAT32 USB drive. HYDRA copies the package to it.
  4. HYDRA schedules a one-time boot from the drive, asks Windows to restart in 60 seconds and closes. Your normal boot order is not changed.
  5. The PC boots from the drive, unlocks the selected cards and starts Windows. If something fails, the error goes to the report and the computer shuts down.
HYDRA Tensor Unlock dialog Select a FAT32 USB drive, with drive D: USB DISK, 115.2 GiB, selected.
Step 3, the drive dialog. Click the screenshot to see it full size.
  1. 1Drive. Only FAT32 USB drives are listed, with their size and free space.
  2. 2OK. HYDRA copies the package. When it is ready, HYDRA closes and Windows restarts in 60 seconds.

After the restart

  • The switch is not saved. At every start HYDRA reads the state of each RTX 4000; when all of them are already unlocked, the switch shows on and is locked.
  • The report is on the USB drive in HYDRA-Tensor-Unlock\Logs\RUN<number>\REPORT.TXT. Every run gets a new folder, so older reports are kept.
  • The boot from the drive happens once. The next restart starts Windows as usual, even with the drive still connected.
  • If you suspended BitLocker, turn it back on after a normal Windows start.

Check the result

The USB drive also gets HYDRA-Tensor-Unlock\TensorCheck.exe. It measures the tensor-core rate of each format for about 20 seconds and compares FP32 accumulation with FP16 accumulation. It changes nothing on the card. Close other GPU work before you run it; with several cards, choose one with --pci.

TensorCheck 1.1 on an RTX 4080: FP16 and BF16 with FP32 accumulation at about 212 TFLOP/s, FP8 at about 424 TFLOP/s, ratio 0.999, RESULT FULL_RATE.
TensorCheck on an unlocked RTX 4080. Click the screenshot to see it full size.
  1. 1Card. The GPU that was measured.
  2. 2Rates. TFLOP/s for each format. After the unlock, FP16 and BF16 with FP32 accumulation match FP16 with FP16 accumulation.
  3. 3Result. The FP32-to-FP16 ratios and the verdict.
RESULTRatioMeaning
FULL_RATE0.85 – 1.15FP32 accumulation runs at full speed: consistent with an unlocked card.
HALF_RATE0.35 – 0.65Half speed: the stock GeForce limit.
INCONCLUSIVEanything elseThe measurement was unstable. Close other GPU work and run it again.
NoteTensorCheck measures speed; it does not read the card's settings. Power limits and other load can lower the numbers. It is not a benchmark of real applications and not a stability test.

If it does not start

HYDRA writes the reason to the LOGGING tab. Secure Boot and BitLocker get their own messages. Other problems use one line that names the step that failed:

NVIDIA Tensor Unlock operation unavailable: unit=T1, stage=S3, adapter=0, code=0x1001, … trace=…
StageStep
S1Platform check (Secure Boot, BitLocker) and choice of cards
S2Preparing the package
S3Copying the package to the USB drive
S4Creating the one-time boot entry
S5Requesting the restart
S6Cleaning up after a failed step
CautionDo not boot from a drive whose copy did not finish. Start Tensor Unlock again instead, and HYDRA updates the package.