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It Is All About BTC, LTC, ETH, DOGE, KAS mining as well as other alternative crypto currencies
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Earlier this month we have mentioned the announcement of the ScryptGuild pool in their Alfa stage with invite only access and now the pool has moved to Beta stage and is open for free registrations. ScryptGuild is a pool with multiple alternative crypto currencies and an automatic switching algorithm that allows you to mine the most profitable crypto at the moment. It is similar to Multipool and the likes of it, however ScryptGuild offer some extra features that make it more attractive. For example you can set only one mining pool and switch to different cryptos to be mined on per worker basis directly from the web interface, there is also an option to directly sell your alternative coins that you have mined for BTC. Not to mention that the list of alternative cryptos is more up to date based on the more profitable coins at the moment and not keeping coins that you will probably not want to mine anymore like in Multipool for example.
ScryptGuild uses PPLNS system for distributing miners earnings or Pay per Last N Shares. This is a payment method which does not allow for pool hopping because it pays for work done previously, rather than paying for work based on the concept of “rounds”. ScryptGuild applies payments to the 5 most recent shifts: The active shift, and 4 recently finished (“open”) shifts. Payments are applied on a per coin basis, using your score on that coin vs the total pool score on that coin. Shifts are closed every hour, one minute after the hour. The pool fee is 2% and the current hashrate of the pool is already about 2150 MHS. You can set the minimum difficulty level starting from 16 and going up for each worker independently, so it is also a goo d place for low hashrate miners such as Nvidia-based GPUs or small Scrypt ASICs like the USD DualMiners.
We have been using the pool for a few days already and like the stability and ease of use, along with the useful extra features that it offers, including the direct sell for BTC from the pool with a slightly higher fee than if you move your coins to an exchange and sell them there (you can still do that if you wish). So we have said good-bye to Multipool and have switched to ScryptGuild completely for our main alternative profit based mining pool. And our backup pool for a while already is LTC Rabbit, though at the moment the extra altcoin bonus that this pool offers is rarely seen and most of the time we are mining LTC directly there instead of alt coins. Still good for a backup pool though as it is stable and runs reliably, so we would still recommend it as a good backup option. The combination between the two pools works like a charm for us, so we do recommend to try it out yourself if you still hasn’t done so.
– To check out the new ScryptGuild Scrypt-based alternative crypto mining pool…
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…
Nvidia is advertising their new GeForce GTX 750 Ti GPUs based on the new more power efficient Maxwell architecture as being with 60W TDP, but in truth they seem to be much more power efficient than that. A lot of people are already interested in using these new GPUs from NVidia for mining, because the performance that the Maxwell delivers seems to be very good in terms of hashrate per Watt ratio. When you use CUDAminer to mine with the GTX 750 Ti you will notice the card will quickly reach the 100% power target limit and normally you are not allowed to increase the power limiter of the card above the 100% value, you are allowed to only lower it further. The interesting thing here however is that the default TDP limit for GTX 750 Ti is actually set to 38.5W inside the BIOS and the minimum of 78% you can go down to is equal to just 30W TDP and as we’ve mentioned Nvidia is talking about 60W TDP for these cards. The fact that the cards are actually limited to 38.5W by their power limiter is something that can prevent you from squeezing the maximum performance that you can get by overclocking the GPU and/or the video memory of the card, so increasing the TDP limit by modifying the BIOS and reflashing the video card with the modified BIOS can help you with that.
Since many of the GeForce GTX 750 Ti video cards do not have external PCI-E power connector you will be limited to the maximum power that these cards will be able to use due to the 75W maximum of power that PCI-E x16 slot can provide by specifications (66W for the 12V line that you will be actually using, the other ~10W are for the 3.3V line). But even this will provide more than enough headroom since the default TDP limit is not 60W as we though, but really just 38.5W, so lots of headroom for overclocking. In order to be able to modify the BIOS of your video card you will need to first save the original one from the card, you can use GPU-Z for that and make sure you keep the original BIOS as a backup and save the modified one as a separate file (you can also backup the BIOS with the nvflash under DOS if you are having trouble with GPU-Z). Then you need to fire up Kepler Bios Tweaker and open up your BIOS file and edit is as shown in the screenshot above (left is original, right is the modified) in order to get 65.5W as the maximum TDP of the card. After that you need to flash the BIOS back to your card using the provided nvflash, you can download the flasher and the Kepler Bios Tweaker along with a standard BIOS from a reference 750 Ti and a modified version of that BIOS to allow 65.5W TDP from the link below. We suggest that you save the BIOS from your own video card and modify it, also do have in mind that modifying and flashing modified video BIOS to your video card can be dangerous, so you should be extra careful what you are doing and not modifying things that you should not or does not know what they are for!
The procedure described above will work for increasing the power target limit on other video cards as well not only on GTX 750 Ti, however before increasing the limit make sure that your video card cooling can keep the card cool enough. Using the video card fro mining will bring the power target to 100% in most cases even without overclocking the card additionally, so just by increasing it you might e able to squeeze some extra performance even without overclocking it further. The version of nvflash provided in the archive below is the latest one that will work with the GTX 750 Ti as well as with older video cards, it is the DOS version of the flasher as the Windows version of nvlfash does not seem to work properly – it does not want to flash the modified BIOS to the card saying that the BIOS digital signature is wrong. No problems flashing the modified video BIOS though trough the DOS version of nvflash 5.163, so we have only included the DOS version that will work with the method described above. There are two BAT files configured to flash the modified video BIOS and to restore the original version of the included reference design board BIOSes, you just need to run “nvflash your_bios.rom” and confirm with “y” when asked by nvflash (make sure you’ve made a backup of your original video BIOS first!). Again, be aware that video BIOS flashing and modification can be dangerous and can temporary render your video card useless, at least until you reflash it with the original BIOS, so do keep a backup of the original! Also note that increasing the TDP limit beyond the recommended value above could also be dangerous, so be well aware that this modification can be dangerous! Feel free to share your results for overclocking and mining hashrate after increasing the TDP limit of your GTX 750 Ti or another board in the comments below.
– Download the Kepler Bios Tweaker tool and nvflash for modifying your video BIOS…
- In: Mining Hardware|Tests and Reviews
- Tags: GeForce GTX 750 Ti, GeForce GTX 750 Ti mining, GeForce GTX 750 Ti TDP, GPU-Z, GTX 750 Ti, GTX 750 Ti cudaminer, GTX 750 Ti mining, GTX 750 Ti nvflash, GTX 750 Ti power target, GTX 750 Ti TDP, increase power limit, increase power target, Kepler Bios Tweaker, Maxwell, maxwell mining, Maxwell power target, Maxwell TDP, nvflash, nvflash 5.163, nvflash download, Nvidia power limit, Nvidia power target, power limit increase, power target increase, Power Target Limit, TDP limit, TDP limit change, TDP limit increase, TDP limit override, video BIOS, video BIOS modification