We have explored that topic a lot in the past weeks.

Have a look at this thread about
(A) optimizing with stock voltage,
(B) undervolting, potentially with your own modified BIOS, and
(C) undervolting and underclocking to a certain sweet spot


The reason for doing this is NOT to blindly increase the khash/s. But to save money by using much less electricity.
(C) results in amazing khash/Watt efficiency:  Almost 3 khash/Watt for the whole rig, and 4.0 khash/Watt for the GPUs only.

Very important for people in countries with high electricity prices, and those mediocre weeks with low coin output.

I suggest to jump into posting #37 now - but if you want to try, please read the whole thread. More reading, but less tears :-)

Exactly. That's why I like the VBE7 approach, to not just flush any other BIOS, perhaps even from a different vendor, but to use the original BIOS, and just tweak 3 values.  Posting #45 gives such a BIOS, and how I created it.

Still, there is enough danger left. Do it at your own risk - and not in all of your GPU cards at the same time.

 

---
 P.S.: Let's spread the word, imagine the altcoin network starts saving 1/4, 1/3 or even 1/2 of electricity.

Nothing like waking up to see a rig's been down almost all night because of an ethernet address conflict... Still beating yesterday even minus a rig lol

if there is no HW errors, disconnects...etc everyone should have 99+% efficiency after few hour (difficulty does NOT matter!)
more hash u have mean less time to balancing out luck/unluck at higher difficulty
but there is no way to be "unlucky" all the time and getting bad efficiency without any reason!

Work Unit = shares / minute @ difficulty 1 (diff1 = 2^16 at scrypt coins)
HRA = average hash rate (kHs)

efficiency = WU * 65536 / 60 / 1000 / HRA
(*100 to get res. as %)

after 1+ week mining i (stil) have more than 99% efficiency on all rig
1h ago restarted my solo card desktop PC = 110% efficiency atm.. and will go down to ~100%

Ideally it would be the same?

I've encountered a lot of material that advises if WU is less than 90% of your hashrate you should fiddle a bit with thread concurrency and intensity settings. It would be better to settle for a slightly lower hashrate with less rejections if that results in a bigger WU.

When I sum up my WU on different rigs, it is pretty close to the accepted hashrate as reported by middlecoin. So I guess WU is the one to look out for, not hashrate.

Probably means PowerTune +10 instead of +20 (I think)

290's are a little weird to configure... one of my XFX's won't run on anything other than 947 (stock clock) lol... It also drops off BAMT 1.2 every once in a while, however, it doesn't affect shares so I don't really care.

One last suggestion, make sure the clocks are stable and not fluctuating a bit. Low watts can cause errors. I turn my 290x power limit to +10 when mining, and get as low as .5% rejected on some pools.

You could also try setting custom intensities for each card, separated by commas (-I 13,13,19,20). You can also use commas on other settings. I don't know the max temp of most of yours, but I do know r9 cards can take up to 94c and be ok (I keep mine at 85-88).

You are running a much higher intensity on that card, causing higher temps.
probably too high.

sorry if this has been responded to but I skimmed through but didn't see it

The part where everyone's hashrate and btc balances were flat... h20 said it was a server issue- are those hours going to be credited back when the server updates?

Thanks

Can anyone list the us severs for me please? i cant find/remeber them 

Middlecoins hashrate is too high. It would crash the coin completely.

there was a chinese language article along with that information from this thread.  the ASIC was presented at an industry conference on Dec 8 in Beijing.

sorry if you are illiterate in chinese moon language lmao

ha ha ha america