Video 小ard Overclocking for Mining: Increasing Hash Rate and Cutting Power Consumption

Hi there! This is another article in the series where I share my experience with beginner miners. Last time, we talked mainly about setting up the rigs; today, we鈥檒l be learning about video card overclocking which is used to increase hash rate and cut power consumption.

What Is Overclocking?

Using special software, we can increase performance of the processor, RAM and other hardware components. However, in GPU mining it makes sense to tinker with video cards only. Actually, it means changing AMD card timings, voltage, and core and memory frequency. Let鈥檚 take a look at how it鈥檚 done on Windows and Hive OS!

Dangers of Overclocking

Before we start, I have to warn you that manufacturers usually don鈥檛 support hardware overclocking. Even if you have a special model suitable for overclocking, it may be somehow limited in terms of functioning. For this reason, we鈥檒l use 鈥渦nconventional鈥 means of overclocking which will most likely result in voiding your warranty, so be careful: incorrect settings may turn your device into a piece of garbage. Proceed at your own risk.

By the way, devices suitable for overclocking are usually more resistant to unsuccessful attempts: you can always switch back to default settings! Non-overclocking devices can be reset only with the help of some special equipment.

Run a Pretest

I recommend you to start by testing your equipment. Do it to get the general idea of its default capabilities. Just start mining for something about five minutes, check the hash rate and temperature, and measure the rig鈥檚 power consumption (if possible).

In my case, one 4 Gb Gigabyte RX 470 video card offered only 21鈥22 MH/s at default settings, about 25 MH/s when overclocked with the popular MSI Afterburner utility, 鈥 and 29.5 MH/s after I changed the timings through flashing.

Overclocking Stage 1: Flashing VBIOS

Instructions given at this step are applicable only to AMD video cards. It took me some time to find information on NVidia firmware modification, and it turned out it wasn鈥檛 worth it. However, make sure to look up info about your model.

VBIOS modification is the most dangerous stage of overclocking, but it鈥檚 also the most important one. Without it, you won鈥檛 be able to make the most of your video cards. There are several things a video BIOS contains information on; among then, there are operating frequencies, voltages and timings of the graphic core and memory. Default settings are usually set in such a manner that helps to provide maximum performance and stability for games, but it鈥檚 preferable to change them if you mine.

To keep this article short, I won鈥檛 go further into theory; let鈥檚 pass on to practice. VBIOS flashing includes three steps: backing up, modifying, and loading back onto the device. If you are ready to risk, try finding a ready-made mining BIOS image. Still, remember that loading a wrong firmware may kill the card.

If your video cards have a BIOS switch, your risk decreases significantly. Even if the video card doesn鈥檛 start, you can switch to the backup BIOS and restore the settings! Just look for a tiny switch on the side of the board.

I suggest we don’t risk it and go through all of the steps. Besides, if your video cards are absolutely identical, you may cut losses and create only one back-up copy.

Creating a VBIOS Back-up Copy

A video card has to be hooked up and properly installed in the operating system. I recommend hooking up the cards one by one so that you don鈥檛 flash an adjacent card by mistake. I鈥檒l also say a few words about NVidia cards, but remember we are modifying an AMD one.

If you are a Windows user, download ATIFlash or NVFlash depending on your video card manufacturer. Linux-based mining distributives generally come with built-in utilities. Another popular piece of software is GPU-Z, but I won’t recommend it: there are massive forum reports describing problems caused by loading the full image.

ATIFlash has a graphic interface. Run the software as an administrator and select the desired adapter at the top; then press 鈥淪ave鈥. It will result in a .rom file. Let鈥檚 give it a name (something like 鈥渂ackup.rom鈥 will do).

ATIFlash may take a lot of time to load, but if nothing seems to be happening after you run the program, the most likely reason behind it is using Windows 10 and an outdated software version. Download v.2.8.4, and it will work!

NVFlash is a console utility for NVidia. Open the terminal as an administrator; in Windows, click 鈥淪tart鈥 鈫 cmd 鈫 a right-click 鈫 鈥淩un as an administrator鈥.

  • Go to NVFlash folder:

cd C:\Users\Administrator\Downloads\NVFlash\

  • Let鈥檚 get a list of video cards and take note of the desired video card number:

nvflash –list

  • Save the original BIOS:

nvflash -i0 -b backup.rom

If your rig is based on Hive OS, it鈥檚 even easier. Open the web interface, then enter the desired rig and go to the Overclocking tab. Select the desired video adapter and click 鈥淒ownload VBIOS鈥. You鈥檒l see a 鈥> *.rom鈥 shown as the rig status. Save it onto your computer. To make sure you selected the right video card, it’s better to connect the adapters to the motherboard one by one. That鈥檚 it!

Also, keep in mind a number of simple actions that may help you to save the video card in case of emergency. Make sure you created several copies of the final .rom file: send one of them to your own email.

Next, we鈥檒l be making some changes to the image.

Modifying VBIOS for Mining

Here, we need to reset the timing values to make the frequency higher than 1,500 MHz (1,625, 1,750, 2,000, and so on). We can do it with the help of the Polaris Bios Editor software that comes in a number of versions. I picked the 1.4.1 one, but you should choose the version suitable for your video card and the memory chip. Setting a wrong version may cause displaying incorrect memory frequencies or not displaying them at all.

Run the program as an administrator (a right-click 鈫 鈥淩un as Administrator鈥).

When you see the message about BIOS modification being dangerous and possibly leading to irreparable damage, click 鈥淥K鈥. Press 鈥淥PEN BIOS鈥 and open the file you鈥檝e loaded at the previous step. Remember, you have to make a copy of this file before making any changes.

After opening the file, you鈥檒l see a pane saying 鈥淭IMING VALUE鈥 (or 鈥淭iming Strap鈥). If it demonstrates numbers different from 0:1500, 0:1600, etc. or there鈥檚 simply no pane shown, try another version of Polaris Bios Editor.

After that, copy the whole row opposite the 1,500 value and paste it into all the rows listed below (1,652, 1,750, 2,000…). To copy, click the value (for example, 7770000000000000022AA1C0鈥) with the right mouse button and choose 鈥淪elect All鈥. Missing even one character will lead to irreparable damage! You can use this utility to change other BIOS parameters, e.g. maximum frequency or fan rotation speed, but timings are actually enough.

Save the file by clicking the 鈥淪AVE AS鈥 button and adding the 鈥淿modded鈥 suffix to the image鈥檚 name 鈥 do so to avoid mistaking this file for the original.

If you can鈥檛 find the right version of Polaris Bios Editor, try Red BIOS Editor. With it, follow the same instructions: load BIOS by clicking the 鈥淟oad鈥 button, go to the 鈥淰RAM Timings鈥 tab, copy the value corresponding to 1,500 MHz into each row below. Repeat that for every memory chip that can be found in the Memory Type list. Finally, click 鈥淪AVE鈥 and add a new file suffix.

Yay! We鈥檝e modified the firmware; now we only have to load it onto the video adapter.

Loading the Modified VBIOS Onto the Video Card

Run ATIFlash as an administrator again; select the same video adapter at the top. If you have several video cards, it鈥檚 better to do it through a console, as video card names shown in the list get cut and you may accidentally modify the wrong card. So, as I鈥檝e already said, it鈥檚 safer to connect video cards to the computer one by one.

This time, click 鈥淟oad Image鈥, select the .rom file from the previous step (the 鈥淿modded鈥 one), then click 鈥淧rogram鈥. Before you do so, close all unnecessary programs, as you鈥檒l need to restart the computer.

It is very likely that everything will be just fine. After the operating system restart, you鈥檒l be able to find the video card with the device manager.

Let鈥檚 take a quick look at some typical firmware issues:

  • Failed to read ROM error has to do with damaged firmware image. If you’ve downloaded it from the Internet, it鈥檚 better not to risk it and find a different file. If you鈥檝e modified it yourself, try again and make sure to copy every character in the timing rows.
  • If facing an error which says聽Cannot find discrete ATI Video Card, make sure the video card is displayed in the device manager. Try connecting it directly to the motherboard, without a riser. Disconnect other video cards.
  • Stop immediately if there鈥檚 a subsystem id mismatch error! It means there鈥檚 something wrong with the firmware size Of course, you may try to transfer the values through Polaris Bios Editor, but it鈥檚 better to find a different image.

If you work on Hive OS, you have to go back to the Overclocking tab and click 鈥淔lash VBIOS鈥. Select the edited .rom file (with the 鈥淿modded鈥 suffix) and the video card index (I still recommend connecting video cards one by one), and click 鈥淯pload鈥.

Congrats, you did it!

Overclocking Stage 2: Increasing Frequency and Decreasing Voltage

This stage is much easier and safer. Our task will be to find memory, core, and voltage frequencies letting the video card continuously offer the maximum hash rate possible. The word 鈥渃ontinuously鈥 is important here: a video card with all its frequencies cranked up might work, but with occasional freezing and errors. This is why we need to find a performance-reliability balance; thankfully, there鈥檚 almost no chance of damaging the adapter at this point.

If you mine on Windows, you鈥檒l need the MSI Afterburner utility. Aside from what its name suggests, it works on both AMD and NVidia video cards. Install the software from the official website, restart the computer, 鈥 and you’re all set.

Afterburner comes in different designs depending on the version, but the structure is always the same: you see a number of categorized sliders, e. g. 鈥淰oltage鈥, 鈥淐lock鈥, 鈥淔an鈥. A good start would be to set voltage as 920 mV, core clock as 1,000 MHz, and memory cllock as 2,000 MHz. Check how the card reacts. Then, depending on the memory chip manufacturer, you will need to either increase these values or decrease them. If the video card fails, try increasing voltage up to 950 mV or decreasing memory frequency down to 1,950 MHz. If everything works smoothly, you can slightly pump up the frequency parameters.

In my experience, Samsung offers the best performance. Its memory cards work continuously at 920 mV voltage, 1,100 MHz core clock and 2,100 MHz memory clock; their temperature and fan rotation speed are pretty reasonable as well (up to 68掳 C and up to 70% respectively). This combination provides an excellent hash rate at relatively low power consumption. If using Windows, you can check the memory manufacturer with the help of GPU-Z.

I wouldn鈥檛 set the fan rotation speed using Afterburner; it鈥檚 better to use the built-in Claymore auto fan. You can activate it through the `-tt 68` parameter, i.e. target temperature.

If you work on Hive, you won鈥檛 need any utilities: everything is already built into the system.

Open your rig in the web interface, and you鈥檒l see the familiar CORE, VDD, and MEM abbreviations included into the video card list. These are the same parameters we’ve seen in Afterburner. To change the parameters, use the button in the rightmost column. Additionally, you鈥檒l see memory chips shown under the video card names. If they are all the same, you can use the button for overclocking configuration on all adapters at once.

The value selection process is similar to that one described above: start at 920, 1,000, and 2,000, and adjust the numbers. In the Hive interface, errors are displayed to the left of the hash rate (check my screenshot: there are 2 errors in GPU-2). If you notice 10 errors per hour or so, it鈥檚 time to finish. If there are no errors and the temperature values are fine, you can increase the frequency.

You can set the fan rotation speed within the same overclocking configuration window, but I prefer to trust Autofan: it does a great job maintaining the necessary temperature (up to 70掳 C) without overloading the fans. Also, this window displays more options for some cards, e.g. OhGodAnETHlargementPill for NVidia cards. Unfortunately, I cannot cover all settings in just one article, so I suggest you look up the exact parameters recommended for your card.

Memory Maintenance

Unfortunately, video card memory tends to wear out. Mining loads video cards in a way no avid gamer ever could. Video adapters may work at full capacity, maximum frequency, and decreased voltage 24/7 several years in a row. To prolong your video card鈥檚 life, follow two simple rules:

  1. Don’t allow overheating. At increased temperature, chips degrade faster, and your card may even completely go out of order because of the critical temperatures. Configure automatic mining deactivation in case the temperature reaches 90 degrees and above. Also, turn on overheating notifications and monitor fan performance.
  2. In case or errors, decrease overclocking. Due to the gradual wear of memory chips, your video card may start displaying more errors than it used to (even if overclocking is being performed at the same frequencies).


Once you’ve completed all of these modifications, leave the rig for 12鈥24 hours and compare the 鈥渘ew鈥 levels of performance and power consumption with the initial ones. In my case, the difference turned out to be 鈮30 % 鈥 a great result!