Posts Tagged ‘Maxwell cudaminer


The GeForce GTX 750 Ti series of graphics cards based no the new Nvidia Maxwell architecture have really captured the attention of crypto currency miners due to their good performance (hashrate) per watt. Nvidia is advertising these cards to have 60W TDP, however we have discovered that the actual TDP limit for the power target set in the video BIOS of these cards is 38.5W…


This made us dig into the matter a bit more in order to see how much power actually does a GeForce GTX 750 Ti draw from the motherboard (a reference GT 750 with no external PCI-E power connector). So we’ve attached a watt meter to the power line of an external PCI-E extender to see how much power is drawn by the GT 750 Ti card. The results we got were quite surprising, even though we knew that the default power consumption should fit in the 38.5W limit for the power target set in the BIOS. With the stock frequencies for the GPU and the video memory the GeForce GTX 750 Ti has shown to draw just about 28W ot power producing about 250 KHS hashrate for Scrypt mining. After getting the card overclocked to +135 MHz for the GPU and +650 MHz for the video memory the power consumption has risen a bit to about 34W average with a hashrate of about 300 KHS for Scrypt crypto mining.

So if you were calculating the power usage of GTX 750 Ti as 60W in order to see the ratio of hashrate per Watt of power, then you should rethink how you calculate it now. Note that this is the actual power that goes from the PSU to the video card, the real power consumption with a 80 Plus certified power supply that provides 90% efficiency for example would rise with 10% to about 30W (stock) and 37W (overclocked) respectively as the actual power drawn by the card from the wall socket.


The Geforce GTX 750 Ti video cards based on the new Maxwell architecture from Nvidia have generated quite a lot of interest among the users mining crypto currencies thanks to their very good hashrate per watt of used power. And after we have tried a reference GTX 750 Ti board that does perform pretty well and overclocks decently to provide some extra hashrate we are now moving to trying out different non-reference design video cards based on the GTX 750 Ti. Out goal is to find the best choice for overclocking and gaining the maximum possible performance for use the GPU for mining crypto currencies. So we took a Gigabyte GTX 750 Ti (N75TOC-2GI) video card for a spin to see what we can get out of that board…


The default Scrypt mining performance with CUDAminer was about 273 KHS, or slightly more than what we got with the reference card at stock frequencies of about 265 KHS. The two advantages of the Gigabyte board were the presence of an external PCI-E power connector and the much better cooling solution compared to the stock cooler. However we have found out that the TDP limit of the Gigabyte was still set at 38.5W in the video BIOS, though with the Power Target limit removal method you can get much higher limit set and avoid the Power Target functionality limiting your performance.


Overclocking the Gigabyte GTX 750 Ti card to +135 MHz for the GPU and +700 MHz for the video memory brought the Scrypt mining performance to about 303 KHS (the maximum stable clocks for mining), however we were hitting the TDP limit. So we have increased the TDP limit to 65.5W by modifying the video BIOS and flashing the modified version on the Gigabyte board and the result we got with the same overclocked frequencies was up to 322 KHS. Unfortunately the Gigabyte board did not allow for higher GPU frequencies that +135 MHz or to increase the GPU voltage higher than the default value. And while 322 KHS with a silent operation and 42 degrees C of the GPU is not a bad result at all, we are going to be checking out other different GTX 750 Ti boards to see if we are going to be able to get a bit more hashrate than that. So stay tuned for more updates on that…


We have already ran some tests of the new GeForce GTX 750 Ti GPU based on the new Nvidia Maxwell architecture for mining scrypt-based crypto currencies such as LTC and DOGE with the help of CUDAminer (up to 265 KHS). The results it is giving, along with the low power usage of the card are making it an interesting option for people that are interested in mining crypto currencies with Nvidia GPUs. The GeForce GTX 750 Ti also shows good overclocking potential for even higher performance (up to about 300 KH/s) on a reference design board. After looking at some non-reference design boards such as ASUS GTX750TI-OC-2GD5 that has additional PCI-E power connector and much better cooling we considered that even higher performance could be achieved, however after checking some reviews of these cards it seems that the Power Target maximum on these cards is still 100%. This simply means that even though the card is clearly designed to handle serious overclocking, the power limiter will not allow you to go beyond the TDP rating of 60W, so as a result it seems that these cards are not overclocking much better than the standard reference boards.


We have also tested the performance that the new GeForce GTX 750 Ti Maxwell cards can offer in some other crypto currencies supported by CUDAminer that do not use Scrypt algorithm, but instead rely on different approaches – SHA-3 (Keccak), Scrypt-jane, Adaptive N factor Scrypt. The performance we got with them was also quite good, though overclocking the card did not help as much these as with Scrypt. Below you can find out what our results were with the different crypto coins we have tried that use the above mentioned alternative algorithms. Note that we are still trying out different configurations in order to get the maximum performance out of the GTX 750 Ti for these alternative crypto currencies, so any suggestions for settings to try with are welcome. As suggested we overclocked only the GPU for the latest results to the maximum of +135 MHz, without clocking the video memory as apparently for these algorithms it does not make sense (downclocking it down with -502 MHz does not seem to affect performance significantly). We are going to update the results if/when we get a better performance with the settings we find to work best for the specific algorithm and crypto coin combination. You are also welcome to request us to test with other coins that are supported by the CUDAminer software.

YACoin Scrypt-jane mining performance with:

cudaminer.exe -a scrypt-jane -o stratum+tcp:// -u yourworker.1 -p password -L 4

Mining YACoin that uses Scrypt-jane has proven a bit tricky with CUDAminer as apparently it did not want to work properly with our custom settings for the kernel settings we used for Scrypt, the only way to make it work was to use the autotune functionality of the miner, otherwise we were getting errors. This means that we could not try our best performing kernel configuration T5x24 on Scrypt-jane here. After trying some suggestions for CUDAminer and YACoin and adding lookup gap with -L 4 (the best performing lookup gap setting for GTX 750 Ti) we got around 1.7 KHS out of the card. Overclocking the GTX 750 Ti to +150 MHz GPU gets us up to about 1.78 KHS of hashrate for mining YACoin (T74x1 automatically selected, so far has the best performance, as setting manually kernel does not appear to work properly).

VTC Adaptive N factor Scrypt mining performance with:

cudaminer.exe -a scrypt:2048 -o stratum+tcp:// -u yourworker.1 -p password -i 0 -l T5x24 -C 1 -H 2

For VTC mining that uses Adaptive N factor Scrypt algorithm with the T5x24 configuration and manual settings got us about 125-129 KHS hashrate with the GTX 750 Ti running at stock frequencies. After overclocking the Maxwell to +135 MHz GPU the performance increase has boosted our hashrate to about 135-137 KHS.

MaxCoin Keccak mining performance with:

cudaminer.exe -a keccak -o stratum+tcp:// -u mGeS2LBCTJvz1Mb4Hfzt5fU1C9C1tYrxuY -p password -i 0 -l K1000x24 -C 1 -H 0

For MaxCoin mining that uses Keccak (SHA-3) algorithm we could also use the K1000x24 kernel configuration and manual settings and that got us about 62000 KHS hashrate with the GTX 750 Ti running at default clocks. Overclocking the GTX 750 Ti to +135 MHz GPU has increased a bit the hashrate to about 72600 KHS.

Meanwhile the author of CUDAminer has released an updated version of the miner software, though it is not yet specially optimized for the new Maxwell architecture you might want to update to it as it has some fixes and improvements. Furthermore there is a mention about upcoming BlakeCoin (BLC) support, so it will be interesting to see what kind of performance the GTX 750 Ti will be able to offer for BLC mining (Blake-256 algorithm) where the typical hashrate is about 3x the one you get when Scrypt mining.