Make sure your running the batch file/devcon as an administrator. If that doesn't work, make sure you have the 64 bit version of devcon if you're running 64 bit windows, and the 32 bit version of devcon if you're running 32 bit windows.

Side note for people who might search this in the future:

The Asus Z270-A WILL NOT RUN 7 Vega. At least not without additional hardware. Its impossible to install the drivers, they'll crash every time no matter how you do it. 6 cards is doable, as long as they're placed in every slot EXCEPT PCIeX16_1. If a card is placed in the first x16 slot, then the drivers will crash while installing if you try to use more than 5 cards. Just a heads up for anyone who might be having this problem.

Edit: Running 7+ Vega on the Asus Z270-A is doable with a PCIe expander. Just make sure no cards are placed in the first x16 slot.

Because lowering voltages past a certain point in the power play table doesn't actually do anything. Use OverdriveNTool to apply the voltages. Also remember that memory voltage is actually core voltage floor, so make sure it's equal to or lower than your desired core voltage.

Even better! I disable the iGPU on all of my systems, so I wasn't really thinking about that. Can anyone confirm whether the vendor defined identifier (DEV_687F) is the same for all the Vega variants (V56, V64, V64L)?

After reading the documentation for devcon, I've found that you can actually just do


Where devcon.exe is placed in the same folder as the batch file. This ought to simplify things a bit.

ROFL. I think we've already established that a fair price is $0.

OverdriveNTool is working fine for me, but I basically only use it to adjust voltages. I use the registry mod for GPU and MEM clocks.


Use the task scheduler to execute your batch file at startup. See here: https://superuser.com/a/929227

Reboot, run the batch file again, and try mining.

Are you running the batch file as an administrator?

That's exactly what it does. Every card can undervolt to varying degrees, so I have different profiles with different voltages for each card. From the OverdriveNTool documentation:

No problem! Just to set the record straight, I didn't copy this from the other guy. I actually discovered this last Thursday, after spending days running through pretty much every other possibility (Linux, virtual machines, etc). Kind of weird how people tend to discover things at around the same time.

I hadn't originally planned on putting this out there, but some other asshole decided to charge a fee for this info. Fuck that guy. Here's a fix for reduced hashrate and a method for running 4+ Vega at full speed while mining XMR.

Basic Users:

1. Use the Blockchain drivers.
2. Open up your device manager.
3. Open up the "Display Adapters" dropdown.
4. Right click on one of your Vega's.
5. Disable it.
6. Wait a few seconds.
7. Right click on the Vega you just disabled.
8. Re-enable it.
9. Repeat steps 4-8 for the rest of your cards.
10. Enjoy mining at full speed with as many Vega as you damn well please. Probably.

Advanced Users:

The previously described process is a bit of a pain in the ass. Let's automate it.

New Procedure

1. Get your hands on the Windows Device Console (Devcon.exe). This will let you disable/enable devices from console.
2. Create a batch file in the same folder as devcon.exe with the following lines in it:
3. This will selectively disable/enable all the Vega cards you currently have in your system. Thanks to bytiges for noting that killing all the display adapters might not be a good idea for those using iGPU.
4. Run the batch file as an administrator at login, or whenever you lose hashrate on your cards. Enjoy never having to toggle the HBCC switch again.

Outdated Procedure

1. Get your hands on the Windows Device Console (Devcon.exe). This will let you disable/enable devices from console.
2. Run the command devcon.exe FindAll * to generate a list of all the currently attached devices and their hardware IDs.
3. Search your newly generated list for "Radeon RX Vega." You should find something like this:
4. The part to the left of the colon is what you need. Shocking, I know. Put that thing into a batch file that looks something like this:
5. Run your batch file at startup as an administrator. Enjoy never having to toggle the HBCC switch again.

FAQ:

Q: So, Mythic, how exactly does this enable HBCC on cards 5-7?

A: It doesn't! HBCC Does nothing to improve your hashrate! Turns out the drivers are just shit and are bugged when Windows first boots up. Who would have guessed?

Q: But Mythic, does that mean I don't need 16 GB of ram to run my cards at full speed?

A: Correct! 4 GB of ram is completely sufficient!

Q: If I wanted to donate some pizza money to the broke ass college student that typed this up, how would I do so?

A: You ask the best questions! I doubt I'll get anything before more well known people/websites copy everything I just said (with no credit, obviously), but here are some addresses just in case.
          XMR: 42e8AWjcirkBDzCNnSjPxeGJeht71kFfWcoxxCWsxe8HZqP29NruDsxcvVSjbKw17AUDepopK7ZYCUn mRvcGS9kBT5XWhMQ
          ETH: 0x74Ed2CA095Dd3aE98D88d5ca1dDb77E752152938