Be careful.
Sometimes you can run  one miner at 2,5-2,6 GHS, but if you add another one to the same system (hub/USB CArd) they will not start up, or just run an  much lower hashrate.
Maybe  because of bad decoupling or too high  power consumption.


BTW

What are you mining right now?=)
I am solo mining  Opensaurcecoin with my humble 8 GHS=)

Default  is 0781=1.6 GHS

To switch from cgminer to bfgminer you need to do following:

System=> printer and devices=> find your  miners, right click=>Properties>>> uninstall drivers.
Do this for each device.
Reboot.
Then reinstall SiliconLabs drivers and you are in.

Sometimes you need o replug miners  in order to run them.

You can try to provide PLL voltage externally....
Dont you have regulated power supply?=)

Or maybe you can create 1,1 V from your 5V power supply by  building  voltage divider;) (If  so, then use high values to avoid  high current loss)

hi, i measured the voltages on violet dot on my Hardware hacked devices (even though i dont think replacing resistors will change PLL voltage)

The voltage is about 1.15-1.19 V

The capacitor is soldered between GND and +5V

Hi,   a few more news from the front:)

 I measured the input voltage  right from the  usb port on the Antminer (Black and Red dots according to Walking Glitch's picture).
First i noticed that there is  massive voltage drop of about 0,3 V. SO my miners getting about 4.9-4.8 V instead of 5,1 or so.
That was my problem, i am using passive cooling, and    need  USB extension cables. I used cheap  and long ones (3 Dollar, 2.5m). Then i measured the resistance of the cable: 100-150 Ohm.  Chinese crap:)
Now i bought  quality ones, and   getting  5,1 V before Antminer  starts mining.

 Second thing I noticed, the miner gives massive ripple to the  usb ports (usb Hub or in my case PCI-USB 3.0 Card).
If the miner 1 suddenly  increase current consumption you will notice voltage drop on  other   miners if they are sharing same power supply.
 For example if on miner1 the  input voltage  peaks to 5,2 (and so the hashrate),  the miner2 will experience voltage drop  to 4,8 V etc.
That is why you can see this bouncing effect in you mining software.: some miner getting faster while others are getting slower  at the same rate.
To prevent this i added additional Tantalum capacitor of 470 µF on each miner (see Picture).  As the result, the miners stabilize MUCH faster, HW drops even more.

Next  i once again tried  Hardware hack:
10K+3,7K gave me stable 2,6 GHS. But saddly enough i could only run one Miner on my PC. If i switch another one,  they both stop mining... (not sure why, since my PSU can provide 25 Amp on 5V rail, perhaps  too high ripples/interference)

After using 2,2K instead of 3,7K I managed to get stable 2,2 -2,4 GHS with two devices at the same time. Since i only can cool two miners right now, i dont know if  running 4 Miner on this mode will be stable. Right now they are running at nominal 2GHS, while hacked ones perform  5-15% better.
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One more thing: I noticed if  input current  falls under 4,7 V the miner stops mining and  switches off.
Guys, who cant run their miner  past few hundred MHS  should measure if there is any voltage drop on the input....



PS
Still no idea how to bring  antminer to advertised 4GHS....
Maybe some  separate  power supply, not just regular USB3.0 Port with maximum of 900 mA. For example connect GND and +5V from other source, and D+ and D- to USB ports.

To the guy with slow miners:
Did you try to start the miner with the lowest possible freq, while powered alone in hub/ separate usb port, and then increase freq slowly, like 10 min for each value?

On page 7 in the datasheet it says you should choose high resistors to avoid current loss through the devider. I Think graphite gived less then kohm of resistance,which leads to massive current from the output.

Hi,
By  drawing   graphite line in R2  you  just shorted the R1 to ground. (graphite has pretty low resistance)

See datasheet here:
http://www.aosmd.com/pdfs/datasheet/aoz1021ai.pdf
The AOZ1021A can provide huge  amount of current up to 3A, and still maintain 0.8V Output.
So by shorting R2  huge current  flowes through  R1 (1K on default).
Most probably you fried R1 (because i doubt it could  survive high current) and FeedBack input is open, thus frequency adjustment doesn't work.

By measuring the resistance with you multimeter  you again connected   output of DC/DC converter to ground, and  high current was forced into your multimeter. If it was cheap one, it may killed something in it, or maybe it was only  a fuse:)

Try to replace R1 and remove  graphite magic:)
Maybe this few cents for new resistor will save your Antminer.
If it helps, don't forget to donate;)

That is strange.
I juts cant run all 4 Antmners at 2 GHS.

3 of them are supplied with power through my 600W PSU (PCI USB 3.0 extension card).
the other one grabs  its energy through usb 3.0 Hub.
But still one random miner has  about 10% HW and runs at 1.8 GHS, while others have 0% HW at 2GHS.

Every time I start BFGMINER  it is always a new miner.

Any solutions?=)


BTW i am mining solo as  lottery ticket:)

it is not clear what voltage do you need for what frequency.
I tried it, read about my attempts few pages before;)

If someone  manages to  overclock Antmineru1 to  stable 4GHS, please let us know:)

No worries, it is common procedure to clean PCB's with  those chemicals.

You can  remove oil with acetone or isopropanol very easily.

I just mine solo with my 8GH/S. I use it as lottery ticket=)
Ans yes, i checked maths, i have  much better odds on winning the whole block  then winning in lottery.

Here in germany, if I will play 6of49 Lottery twice a  week for  about 20 Euros, i will spend 960 Euro total for tickets.  My average win will be around 530 Euro, so i will  even lose money on the long run (what a surprise ).

With my 8GH/S   for 300 Euros I have  3% chance to find a block in one year.
OK, lets take in account the difficulty will increase(even if i think that it will not grow exponentially  forever, but rather will stabilize  very soon), but  even so i have better odds while mining solo;)

Can someone please explain me, why do so many people rent  (for example) 2xAntminer for 24 Hours for like 5 Euro on ebay?
It doesnt make any sense to me.

just use  old command: --bmsc-freq 0781

Hi, im am currently selling my Antminers via ebay:http://www.ebay.de/itm/221354427920?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1558.l2649.
I can make you small discount if you buy it outside ebay (so i will not have to pay 10% of selling price)

Guys with  high HW rate.
Try to use  BFGMINER.
I had the same problem, and with Bfgminer i have 0% HW