All About BTC, LTC, ETH mining as well as other alternative crypto currencies
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.
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://yac.coinmine.pl:9088 -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://stratum.vertco.in:8080 -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://maxpool.1gh.com:17333 -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.
We’ve been playing a lot today with the new Nvidia GeForce GTX 750 Ti graphics card based on the new Maxwell architecture from Nvidia, trying to overclock it as much as possible in order to get the best possible Scrypt mining hashrate out of the card using CUDAminer. The GTX 750 Ti card we have is a reference design one and it is a bit limited in terms of overclocking options, though we have tried pushing it to the maximum possible values to see what hashrate we can squeeze from the new GPU. We have already gotten about 265 KH/s with the default settings of the card, but overclocking it has increased the performance up to almost 300 KH/s whill still in the 60W power consumption (maintained by the power limiter of the graphics card).
As you can see from the screenshot above our reference design board does not allow user control of the voltage and does not provide an option to increase the power limiter past the default value of 100%. This is done due to the fact that the TDP of the card is set at 60W and the board has no additional PCI-E power connector available, so it needs to fit in the 75W maximum power that the PCI-Express slot can provide to the card by specifications. We have pushed the GPU to +135 MHz which is the maximum value that EVGA Precision and MSI Afterburner give us available and the video memory to +650 MHz as the maximum stable value resulting in about 297 KH/s hasrate that can be squeezed out of the 60W TDP (100% power limiter).
What we have to do now is look for alternative boards that do not follow the Nvidia reference design and that do have more headroom for overclocking – PCI-E power connector and the ability to increase the GPU voltage along with the option for more than 100% for the power limiter. This can give us the ability to squeeze some more KH/s from the GTX 750 Ti as the GPU is clearly handling overclocking very well and can most likely handle even higher clocks without increasing too much the power consumption. As you can see with the fan of the very small and basic stock cooler at 100% the operating temperature of the GPU is just about 54 degrees Celsius, so with a better cooler higher clocks should not be a problem at all… after all 60W is something that is not hard to cool at all nowadays.
We have just tried the card on a x16 PCI-E extender and there seems to be a problem with the normal operation. The fact that the card needs 60W over the PCI-E slot and has not external power over PCI-E power connector can cause problems if you wish to use extenders that do not have molex power connectors. So if you plan on using GTX 750 Ti with extenders it will be a wise idea to go for cards that do come with PCI-E 6-pin power connector on them to save some trouble. The x16 PCI-E extender we have tried works just fine with a Radeon R9 280X card, so the problem is not in the extender.