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Archive for the ‘Tests and Reviews’ Category

Status Update on Our PB Mining BTC Cloud Mining Service Test

28, Feb 2014

pbmining-5-year-btc-mining-contracts

We’ve been using the PB Mining Bitcoin cloud mining service for almost a week already and since the BTC network difficulty just increased by about 21% we have decided to report on our current earnings with the previous difficulty. We have started testing the BTC cloud mining service by purchasing 1 GHS with a price of 0.0107 BTC per GHS for the purposes of our tests. Now, after the difficulty has been just increased the there is a new price of just 0.0089 BTC per GHS. This means that at the moment you can purchase 500 GHS for about 4.45 BTC as opposed to 5.35 BTC for the same hashrate last week. This price reduction with the increase in Bitcoin network difficulty is a good thing and makes the service even more attractive, so we are already considering of purchasing some more GHS.

pbmining-current-earnings-status

Let us see how things are going in terms of earnings, since our testing has started we got a small payment (they are sent every Sunday before Midnight) and currently our earnings from the 1 GHS purchased equal 0.00075838 BTC (not including the payment that was already sent). These earnings are for mining in the last 4 and a half days after we got a payment on Sunday. With the previous difficulty the estimate was 0.0001607 BTC per day earnings with 1 GHS hashrate so for 4.5 days this equals to 0.00072315 BTC and for 5 days 0.00080350 BTC. With our current earnings in between these two numbers we can say that we are very happy with the results we are getting so far. And with the update of the price for 5 years mining contract the PB Mining Bitcoin cloud mining service is getting more and more attractive option. Sure there are other alternatives available, but they try to not only sell you higher priced GHS, but also make you trade them while they mine for you in order to get higher profit (or loose more trying to do that). This service on the other hand is a long term contract where you cannot sell your purchase GHS, however they will continue to mine for you for 5 years with expected return of investment in roughly 6-8 months currently estimated.

– For more information and to try out the PB Mining Bitcoin cloud mining service…

A Bit More on the Actual Power Usage of GeForce GTX 750 Ti

28, Feb 2014

geforce-gtx-750-ti-power-usage-test-setup

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…

geforce-gtx-750-ti-power-usage-results

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.

First Impressions from the DualMiner USB Scrypt ASIC

27, Feb 2014

dualminer-usb-scrypt-asic

This week we have finally received a DualMiner USB Scrypt ASIC based on a single Gridchip GC3355 processor that is capable of mining both BTC and LTC or only LTC (SHA-256 and Scrypt), so we can share some of our first impressions already using the device for a day. The device uses a dip switch to switch between the mode active at the moment (LTC and BTC and LTC Only) and there are two virtual COM ports available – one for BTC or other SHA-256 and one for LTC or other Scrypt crypto mining (you need to install a virtual USB to COM driver from here). When you are in BTC and LTC mining mode you are supposed to get about 500 MH/s for SHA-256 (BTC) along with about 40 KH/s for Scrypt (LTC), however we are and you are also probably going to be more interested in the performance of the LTC (Scrypt) mining mode only as this way the ASIC uses less power and provides more performance and you better go with 70 KH/s LTC instead of 40 KH/s LTC and 500 MH/s BTC nowadays. One important thing is that when the device is in LTC mode only you need to use the BTC COM port (the first one) and when operating in Dual mode the first COM is for BTC and the second for LTC.

cgminer-dualminer

DualMiner USB Scrypt ASIC uses a modified version of cgminer that comes along with an extra GUI that might be more appearing to the new to mining users, however we prefer to use directly the cgminer from the console (version 3.1.1). The extra parameters you are passing to the cgminer include “–lo” for the LTC only mode (Scrypt only), “-S //./COM12” to set the COM port used by the device and “–dualminer-pll 850” to set the operating frequency of the chip. When you switch to LTC mode only the ASIC increases the voltage to 1.2V and uses 850 MHz to achieve 70 KH/s, in BTC & LTC mode apparently the voltage is 0.9V and the clock frequency is 550 MHz for 500 MH/s and 40 KH/s respectively. You can try increasing the MHz value a bit to about 900 to squeeze a bit more performance, though you should be careful as not all devices apparently can work at that frequency and you better have some sort of extra cooling.

dualminer-scryptguid-hashrate

Our tests show that when the device is used in a pool, the reported hashrate is a bit above 70 KH/s, the screenshot is from ScryptGuild with difficulty set to 16. You need to set the difficulty for the worker lower in order to get good actual performance due to the not so high hashrate of these miners. For the first 24 hours our DualMiner USB Scrypt ASIC has managed to get away with just about 0.15% HW errors running at 850 MHz with an extra fan for better cooling, s things are looking pretty good. We are going to perform some more tests and publish them here in the next few days, so stay tuned for more information abut these USB ASICs based on Gridseed’s GC3355 chips. And while we like how things are working with this low power Scrypt ASIC, we are not going to recommend the purchase of single units due to the low hashrate that each device provides and if you are going to invest in more of these USB ASICs, then you might want to check out the 5-chip Gridseed miners supposed to offer 300 MH/s per devices – these will cost you less for the same total performance. For the moment the price at which the DualMiner USB ASICs are being sold they are not that attractive choice, and we have ordered one just to play around with it. We are waiting for one of the larger 5-chip units to arrive in the next few days, so we are going to be reviewing it as well soon.


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