I am not certain if raising voltage will assist with higher core clock without throwing invalid shares, but what I did was merely reducing the mem clock until no error was thrown. If increasing voltage will allow the HBM memory to hash at expected hashrate I would have done so. But so far it doesn't seems to be the case (able to push to 930 mem clock, but no amount of voltage bump will fix the invalid calculation error).

Yeah maybe. I thought it was common to get them to run 1100mhz.

temp is around 55-60 fan rpm 3000-3500. bit higher becouse i use Onda B250-D8P. its close by GPUs.

pushing memclock to 930 is can. but show invalid shares.   940 is unstable. 

i have this 3 pics,all of cards have Hynix HBM. so,i set up memory clock 890@900mv core 1400mh stable.with ~1800H/s.
powerplaymod is working fine same AIB card's.

Yes, when reference cards were made, only Samsung had HBM2 available. The aftermarket cards were late in part because Hynix wasn't ready.

Anyone mining ETH+PASL or PASC? what's your profitability daily?

I'm running 2016/1600 and 2016/1736. Both have the same issue.

I've been following the reddit definitive guide and it mentions no problems with those intensities.
At some point I remember lowering them to 1920 / 1524 but was not stable either.

Can you suggest some intensities to try ?

PS: yes, I don't like running closed source. I even compiled stak-amd myself, but it makes no difference vs. the stability issue above.

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 how you run 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 that fucker.
6. Wait a few seconds.
7. Right click on the Vega you just disabled.
8. Re-enable that fucker.
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.

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

370W and 720W total.

make sure you have fan RPM enough to keep memory cool.
and gandalf's cast xmr does better with vega56 than xmr_stak

And I repeat, its not carved in stone every vega can do even 1100mhz hbm Cool it down or lower the clocks like suggested.

make sure you have fan RPM enough to keep memory cool.
and gandalf's cast xmr does better with vega56 than xmr_stak

Seems like a normal difference between 56 and 64(~3%)? Considering theres over 10% more shader cores on 64, 56s with 64s bios do well.

Maybe your 56 cant handle 1100hbm? I have 2 64s, 1100 and other is 1065 hbm capable.

This PSU has only 6 pci-e power cables? How are you going to have 8 cables for 4 vega's?
And what if it becomes profitable to mine eth or dual? Then your psu will be not enough

Only if it is Platinum-rated.  Otherwise, if gold rated, 80% rule of 850 is 680.  680-520 = 130 headroom for another Vega, I wouldn't do that on mine.