Seems like Bitmain is resorting to tactics we do not like for their Bitmain Z9 Mini ASIC miners in order to push the sales of the new bigger Antminer Z9 SIC miner, like removing the options to overclock the newer batches of the devices. The initial Z9 Mini miners had a drop-down box that allowed you to easily select the operating frequency of the miner’s chips and since the Z9 Mini do overclock pretty well and work 100% stable with 50% increase in their mining performance it is something that you should do right after you get the device out of the box. The 10 K/sol Z9 Mini at 250W of power usage at the default 500 MHz can easily do 15 K/sol when overclocked to 700 MHz without problems at 350W and maybe even more if it manages to be stable at 725 MHz or even 750 MHz, though not every unit manages to do so.
How do we overclock the new Antminer Z9 Mini miners from the web-based interface when under Miner Configuration, Advanced Settings all we see under the Frequency drop down menu is Balanced that represents the default frequency of 500 MHz? It is actually really easy as what Bitmain seems to do in order to limit the overclocking functionality was to remove the options from the HTML code of the page, so you just have to edit the source code of that page and add the options yourself in order to be able to set the clocks higher. There are number of ways you can do that, but the easiest one probably is to just edit the page code on the fly using Chrome or Firefox and Save&Apply the settings directly, so the device starts to operate at the higher frequency. What you have to do is hover the drop-down box where only Balance is available and right click on it selecting Inspect or Inspect Element. You will see that there is a commented option for Turbo set at 550 MHz as a value, you can edit this one by removing the commenting brackets at the start and end of the line or even just change the frequency of the Balance option to let us say 700 MHz. Just select the line of code and right click on it choosing Edit as HTML from the pop-up menu and do the needed changes.
When you finish editing the line you just apply the changes and you will see them active on the webpage immediately, do not worry, the change is just temporary, so that you can click on Save&Apply to get the new operating frequency saved in the miner’s config file. After the page reloads the changes you have made to the code will be gone as they are not permanently saved. Our advice is to start at 700 MHz as everything should be stable there and you might have to manually increase the cooling fan speed to have thing run cooler and stable as you overclock. Then you can try increasing the operating frequency further to 725 MHz and 750 MHz in order to see if you can squeeze some extra performance with the device remaining stable.
The Bitmain AntMiner Z9 Mini running at 700 MHz should be able to produce about 15 K/sol average hashrate without any problems and continue to run without errors 24/7, so you an get 50% performance increase with just 100W of power usage extra for free. You can guess that Bitmain doesn’t want you to have that bonus and that is why they probably have removed the option from the web interface, though again it is really easy to still overclock your miners despite that. The interesting question here is if the new bigger and more powerful AntMiner Z9 ASIC miner will be just as easy to overclock and as overclockable at the Z9 Mini, or maybe Bimain will have it overclocked already when they ship the device…