Overclocking while mining is extremely important, each GPU is different and allows for it to achieve different hash rates at different clocks. This is because of the difference in components and the silicon wafer in the GPU dye. This means that each overclock will be different per card, but can be relatively the same if the GPUS are the same and were made in the same batch. This is why we can see higher end models of cards, like the Asus Strix series, hit higher boost clocks without the user having to set a manual overclock.
Why Should I Overclock:
Overclocking your GPU while mining has many benefits. The major one being the increased hash rate along with a lower TDP or power used. This makes your GPUS more efficient, mining more coins while using less power. Overclocking also lowers the GPU temps, both the dye temp and the memory temp. This will increase the life span of a card, as there is less stress on it. Setting up your mining rig like this will also put less stress on the PSU, cables running to the GPUs and motherboard as this will also decrease the power the GPU takes from the motherboard. Because of all the reasons listed above this will also make your mining rigs more stable, creating less down time which means more coins!
What are Safe GPU Temperatures:
I generally keep my GPUs between 44 degrees Celsius to 65 degrees Celsius. This is well within the operating temperatures of these GPUs and has proven to be extremely stable. I do not own any cards with memory temp sensors but they have all been taken apart and had both the thermal paste and thermal pads replaced. If this wasn't enough to keep it in my desired range, I would then add some extra heat syncs onto the backs of the GPUs to help bring the temps down more. In my opinion I would never want to run my GPUs for an extended period of time above 70 degrees Celsius or below 35 degrees Celsius.
How to Start Overclocking:
Today we will be using MSI Afterburner to test our overclocks and then translate them over to T-Rex Miner. I have a guide here on how to use T-Rex and the many benefits you gain when using it.
The best way to start overclocking is with the power limit set to 100% on the card, because the GPU memory speed is the most important factor when mining coins like ETH we will start by overclocking this. After you have installed MSI Afterburner start with the Memory Clock around +300 and jump up +100 after a minute or two. Continue to do this until the miner displays a drop in hash rate or the card becomes unstable. When this happens decrease the Memory clock by 100 and step it up by +25 or +50 and see if it is stable there.
Overclocking the Core:
On a lot of the newer 20 series or 30 series cards it is important to actually lower the GPU core clock. As mentioned before coins like ETH mainly use the GPUs memory, and decreasing the core clock will allow us to drop the power limit more and lower temps. Start with -100 and moderate the hash rate, if it goes down slowly go back up by +25. If nothing changes continue to lower the clock by -100.
Lowering Power Limit:
I've noticed from the cards I have overclocked so far a good starting point is around 70%. Set your power limit here, moderate the hash rate and if there is no drop continue to drop the power by 5%, when you start seeing a drop in hash rate then go back up by 1-2%. Do this until you reach about the same hash rate you had before moving around the power limit and save your settings. Take these over to you preferred mining software and you now have the best OC settings for your GPU!
I Found Settings Online:
There are many websites that show you the average overclock for your GPU, these normally are fairly accurate but will not be the best for your GPU. A lot of the time the power limits are slightly higher and because these settings are taken from a number of different GPUs, they will include lower end ones or even settings from users who have not fully tested their card. Normally these settings will display a power limit difference of 10-20 watts and a MH/s difference of around 2-5MH/s. Make sure you overclock your own GPU if you want to achieve the best results.
Why is my Hashrate Low:
If you have followed this guide and your hashrate is lower than expected then here are a few reason why. You might have an LHR GPU which limits the hashrate. Nvidia implemented a limiter to try and keep miners away from buying GPUs so that gamers could have better access.
You might have a large difference between your hot spot temp and your dye temp. Download GPU-Z and check this in the sensors tab, generally you don't want the hotspot temp more than 15 degrees Celsius off from the dye temp.
You might have lost the silicon lottery. Some GPUs have a worse wafer than others and its just down to the luck of the draw.