You can change it in the Farm->Overclocking Tab. Default state is 5, min = 1, max = 7 (this is from tooltip). And there is no reason to change those settings for rx6800 as far as i know.
Why do you set MVDD to 800? That probably ruins your hashrate
It seems like it doesnt matter what I set the maximum I get is 52 Mh/s and this is worse than my rx5700 with 54Mh/s
Okay when I run my Rx 6800 alone without my rx5700 it`s hashrate increases to 57Mh/s
I just wanted to say that this whole discussion has been very informative for getting my cards to at least 61/62 MH/s for my 6 x RX 6800 XT cards. I figured out that power was my issue when trying to configure them. It seemed like when you change a GPU overclock that it affects all the GPUs. After about 2 hours of straight tinkering with settings I was able to get 373 MH/s for my rig. I’m satisfied for the time being with my settings. It has since dropped down to 372 MH/s, which is still good. This is with TeamRedMiner. Here are my settings:
My power supply is the Delta 2400W Server PSU from Parallel Miner with 2 breakout boards on a 20 amp 240v circuit.
I just set up a new rig with some Sapphire Pulse 6800s but for some reason my HiveOS isn’t recognizing them. I’m getting “Error matching card number in /sys/class/drm/card*/device/pp_tables”. Any ideas what I’m doing wrong? Here’s a screenshot if it helps…
Old version of the hiveos, try the stable one.
I’m using this one in the image bellow, same GPU as you
lower core than you but more W ? oO 
I’m using phoenix. maybe because of that? no choice of miner since I use 2 NVIDIA card on the same rig
Hi folks, here is the update : I have now 2 rigs 6x rx6800 Sapphire cards. One of them is an 6800XT, sent by mestake instead of a regular 6800 by ebay seller 
Phoenixminer does not work at all by now, not one single version with these cards. But guess what, Gminer is doing awesome job, better hashrate, far more stable then phoenixminer. I am very happy with it.
One single downside though : Gminer eats up slowly my free ram. No idea why. After miner reset, the free ram resets also. I happens only on the 6800 rigs, the NVIDIA has not this issue.
Gminer developers : please make junction temp display happen! Thank you!
Hi there! I’m new into mining and started with 6800 cards. I’m getting a solid 63.30 - 64.00 MH/s with a power consumption of about 113-114W (tested with different miners).
Thanks man help me a lot!
Dont you have any issues with the 650mV core? I got it to 700mV at ~120W
I’ve no problems with 650mV core. The cards are running stable. 
do they last at least a couple of weeks without a restart?
Has anyone come up with any decent settings for the ASROCK RX 6800 yet?
I have two of them on the system, 1 does 58.8mh/s (161w) and the other 58 (157w) with exactly the same settings.
No clear reason why at least to me. I have tried other settings as well but these have been the more stable ones.
Compared to the powercolor rx 6800 on the same rig that does 63.17mh/s at 123w, this is rubbish.
try updating the vbios, I had around 10% difference in windows.
Updated the VBIOS with the one from techpowerup (ASROCK cards 6800) and the mh/s remained the same but power usage went down 40w per card. So partial win 
Now someone with good settings please!
Anyone tried mining DBIX with these cards. using phoenixminer 5.6d both my 6800’s actually boot for one thing, and run around 64mh/s in hiveos. All my Nvidia cards run slightly lower on DBIX though. Very interesting why the 6800’s run so much better on this coin, any thoughts?