All About BTC, LTC, ETH mining as well as other alternative crypto currencies
Normally when you run a multi-gpu mining rig you are monitoring the operating temperature of the GPU and if it is keeping an acceptable level, then you think that everything is fine and may not pay attention to other components. We have done an interesting experiment with a Gigabyte GeForce GTX 970 WF3OC-based mining rig taking thermal images of the back of one of the cards in the setup while it is mining Ethereum and while it is mining Decred. As you probably know the Dagger-Hashimoto algorithm used by Ethereum is heavier on the memory even though the total power usage is lower while Decred and the Blake-256 implementation it relies on is more power hungry and not so dependent on the memory.
The power usage of the GTX 970 while mining Ethereum is around 150 Watts while mining Decred it goes to about 175 Watts. The GPU temperature of the GTX 970 while mining Ethereum in the test mining rig is around 68 degrees Celsius while mining Decred it goes to about 75 degrees Celsius. This of course is with custom settings for the fans, because normally Nvidia wants to keep the target temperature at 80 degrees Celsius, but that might not be that great for 24/7 mining. But if you look at the back of the GPU with the help of a thermal camera you can find pretty interesting things like the fact that the backside memory chips that do not have cooling like the ones on the front of the card actually get pretty hot. A bit too hot if you ask us especially in the case with Ethereum mining with their temperature reaching about 105 degrees Celsius while the back of the card itself remains at not more than 75-80 degrees. In the case of Decred mining, even though the total power usage is higher, the memory chips remain with over 20 degrees lower temperature and the back of the card is similar in temperature, so the difference of the overall temperature is not that big.
So if you are mining Ethereum, especially if you are getting into it just now, you might want to be sure that the GPUs you are using have better cooling on all of their memory chips, including the ones on the back of the card if there are such. While there might be no issues in short term with such higher operating temperatures of the video memory chips, on the long run temperatures of over 100 degrees Celsius might cause you hardware issues and you would want to avoid these on a mining rig that needs to fun 24/7. Do note that while this experiment was performed on Nvidia-based hardware you can expect to see similar results on AMD-based video cards as well with Ethereum driving the temperatures of the video memory higher than other mining algorithms.