I honestly think that the way you have detailed your results and posted them will entice others to mod their gear and
Keep them S1's running.
Great job sidehack, truly appreciated
Trends
Topic: AntMiner S1 Underclocking, a thorough discussion - page 3. (Read 8332 times)
Others might like the info. I like to be thorough, after all. Really I should have done this a couple months ago, but I didn't worry a lot about messing with S1 because I've only had two since about June and, here at the shop, power is cheap enough that they're still slightly profitable at stock settings (about a nickel a day, but still).
Maybe in the next few weeks I'll do the same for a Tube. Novak's already posted instructions on hacking a USB BE into a USB serial adapter for them, after all.
Maybe in the next few weeks I'll do the same for a Tube. Novak's already posted instructions on hacking a USB BE into a USB serial adapter for them, after all.
No I'm fine with the info sidehack.
I've done several resistor change outs on the S1's I just thought you had done something a little different.
thanks
Trends
I've done several resistor change outs on the S1's I just thought you had done something a little different.
thanks
Trends
That is correct. The divider pair on mine was 8200/9760. As an example, on mine I used a 5K6 resistor across the 8200 which (for ease of installation and because I had a through-hole resistor) I tied between the junction of the two adjacent resistors and the high side of a nearby output cap. That requires much less precision than attaching leads directly to the pads of a 0603 SMD component. I measured between 0.815 and 0.825 in a quick check of VRMs on the board after modification, variance mostly due to the 5% tolerance of the 5K6 resistor.
On one VRM I did replace the 8200 with a 3K3 5% and got the same results. I can post pictures of some things later on if desired. It probably wouldn't hurt to put up information about changing clock speeds as well, as that requires SSH and config file editing. I'll also include info on calculating the hex values for various frequency setpoints and the expected hashrate calculations.
On one VRM I did replace the 8200 with a 3K3 5% and got the same results. I can post pictures of some things later on if desired. It probably wouldn't hurt to put up information about changing clock speeds as well, as that requires SSH and config file editing. I'll also include info on calculating the hex values for various frequency setpoints and the expected hashrate calculations.
So just to be clear
"Parallel R: The resistor value required in parallel with the VRM feedback resistor, to achieve Vset" is the value of the resistor (calculated?) to add to R3, R66, R38 or R52 if R3, R66, R38, R52 are left in place.
Correct
I'm not entirely sure. The only problem I had with timeout settings was at the 200MHz neighborhood (200, 196, 193). At timeout 70, the draw current would bounce between about 0.8A and 0.2A (idle) as chips would start to hash, and then all drop out. I'm assuming something in the communication between controller and ASICs was hosing it; once I set timeout to 80 everything worked wonderfully.
The only thing I really saw affecting the HW rate was a Vcore too low at a particular frequency. It makes sense, as in CMOS ICs all the switching is done by charge displacements; higher voltages are required to push a given charge through a given impedance faster, and higher gate charges are required to meet source-drain impedance thresholds for switching. Setting the voltages too low will keep the weakest transistors in the IC from switching effectively, introducing bit errors in the pipeline and returning bad data.
Someone with more software knowledge of Bitmain hardware can probably tell you more about what the timeout setting actually does. I've focused so far on the hardware.
The only thing I really saw affecting the HW rate was a Vcore too low at a particular frequency. It makes sense, as in CMOS ICs all the switching is done by charge displacements; higher voltages are required to push a given charge through a given impedance faster, and higher gate charges are required to meet source-drain impedance thresholds for switching. Setting the voltages too low will keep the weakest transistors in the IC from switching effectively, introducing bit errors in the pipeline and returning bad data.
Someone with more software knowledge of Bitmain hardware can probably tell you more about what the timeout setting actually does. I've focused so far on the hardware.
sidehack
how would the T/O settings affect the HW error rate?
how would the T/O settings affect the HW error rate?
very nice overview! Im picking up some s1 units this weekend to undervolt a little bit and now i think i know where to aim for if i want 1w/GH 
Having recently acquired some AntMiner S1 that another miner in my acquaintance was disposing of for the cost of shipping, I decided to see just how efficiently these little guys could run. With that in mind I set up a test to measure the board-level DC power draw of the mining hardware at various parameter setpoints of core voltage and clock speed.
I connected a controller to a single hashing board with three VRMs disabled. The fourth VRM was wired for precise manual output voltage adjustments in the range of 1.20-0.60V. The controller and fan were powered separately, so only the power required by the single enabled VRM and its bank of 8 ASICs was measured (the idle current from the controller-powering 3.3V buck is considered negligible).
I used a 12V server PSU as the power source, delivered through a 0.1ohm 1% shunt resistor across which I measured the voltage drop, for input current calculations. I used an oscilloscope for the DC power input (measured at the board's connector, below the shunt) and the VRM output voltage (measured at the output capacitors). It was observed that the fan would pull 12V 1A at maximum speed, and the controller (managing 64 ASICs at 250MHz) consumed 0.34A at 3.3VDC; the maximum additional power draw past board draw, then, is expected to be around 13W. At lower board power consumption, the fan requires much less power; assuming half power for the fan, additional power draw would be around 7W.
I included stable voltage ranges for every 25MHz from 400MHz down to 150MHz, and included the stock setpoint ([email protected]) and the AntMiner S2 stock setpoint ([email protected]) for references. The durations of tests varied, most being between 8 and 20 minutes before sample data was recorded. I tried to run up at least a DiffA of 3000, but sometimes I got distracted and ran more; other times, I got impatient (especially during slow-clock tests) and cut it off at less (typically the 20-minute point). For the first batch of samples (400MHz) I reset the voltage after each dataset was recorded, but did not reboot the device. The calculated error data for each sample at 400MHz is based off the DiffA and HW deltas from the previous sample. For all other samples, the machine was rebooted after setting Vcore.
All measurements were taken on an AntMiner S1 with a build date of 2013/11/18, with a VRM feedback resistor pair R3/R12 of 8200 ohms and 9760 ohms, respectively. All resistor modification calculations are based on this pairing.
GH Expected: Expected gigahashrate for a bank of 8 chips at the setpoint frequency
GH Total: The total expected hashrate for a 64-chip S1 at the setpoint frequency
GH Measured: Reported average hashrate during the measurement period
DiffA: Reported DiffA by the end of the measurement period
HW: Reported HW (hardware errors) by the end of the measurement period
Volts in: DC line voltage into the hashboard, measured at the board terminals
Current in: DC line current into the hashboard, measured across the input shunt (see above)
Power in: DC line power into the hashboard ( Vin*Iin )
Vcore: Measured average VRM output voltage during the sample time
W/GH: The power per measured gigahash-per-second ( Pin/GHM )
HWE Percent: Percentage of hardware errors for the sample period ( HW/[DiffA + HW] )
W/GHE: Watts per expected gigahash-per-second ( Pin/GHE )
Vset: The VRM desired-setpoint voltage, to 0.01V
Replacement R: The resistor value required to replace the VRM feedback resistor (R3, R66, R38, R52), to achieve Vset
Parallel R: The resistor value required in parallel with the VRM feedback resistor, to achieve Vset
Noteworthy data points:
- 350MHz @ 1.12Vcore, stock S1 setpoint
- 196MHz @ 0.77Vcore, stock S2 setpoint
- 225MHz @ 0.77Vcore, maximum S2 stability point at stock Vcore
- 200MHz @ 0.72Vcore, minimum stability point at 200MHz - some ASICs were unstable below this voltage, causing resets
- 175MHz @ 0.69Vcore, hashrate reports low due to one chip dropping out entirely; remaining 7 hashed well (average 1.39GH, expected 1.20)
- 150MHz @ 0.69Vcore, minimum stable at 150MHz. At 0.68Vcore all chips dropped out and reported 'X' in ASIC status
I currently have a full machine modified for operation at [email protected] (using a 5k6 5% parallel resistor), for which the expected output is 128.0GH at a total power draw (including half-power 6W fan and 1W controller) of about 133W. I measured the power draw at 11.34V 11.52A (using a 1% 0.05ohm shunt; the PSU interface board's 5% shunt measurement reported 11.43A), for 130.6W DC power consumption. The current stats, at 0h 31m 53s operation, are 128.61GH, 59HW, 56191DiffA
This equates to a DC efficiency of 1.02W/GH with a hardware error rate of 0.1%
The fan is reporting 1020RPM, temps 41/43C in a ~65F ambient environment
A note on the maximum S2 stability point at stock Vcore: the S2 uses the same VRM hardware ( 53355DQP monolithic synchronous buck driver ) as in the S1 (and also ASICMiner Cubes and Tubes). Because the S2 is clocked and volt-set to a lower operating point, each ASIC draws far less current than the ASICs in a stock-set S1. The S1 allocates 8 ASICs per VRM; the S2 allocates 16. Therefore, at any particular setpoint on the S1, the power draw per VRM for the same setpoint on the S2 is doubled. If an S1 is stable at 0.77Vcore 225MHz, it is logical to think the S2 would be also. However, the power draw from the S2's VRMs would be twice the 12.62W seen by the S1, at 25.24W. Assuming a 90% efficient regulator (which efficiency typically drops as current increases, due to parasitic resistances in the inductor and drive FETs), that's an estimated output power of 22.72W; as we're outputting 0.77V the current draw is then 29.5A. The 53355DQP is rated for 30A, which means that you're stressing it to 98% capacity continuously. With a best-case efficiency of 95% (and a few other assumptions, to make the comparison easier), the output power is 23.98W, with an output current of 31.1A, a good 3% past rating. With this in mind, it is probably a terrible idea to try and clock an S2 up to 225MHz even if ASIC cooling was adequate.
I connected a controller to a single hashing board with three VRMs disabled. The fourth VRM was wired for precise manual output voltage adjustments in the range of 1.20-0.60V. The controller and fan were powered separately, so only the power required by the single enabled VRM and its bank of 8 ASICs was measured (the idle current from the controller-powering 3.3V buck is considered negligible).
I used a 12V server PSU as the power source, delivered through a 0.1ohm 1% shunt resistor across which I measured the voltage drop, for input current calculations. I used an oscilloscope for the DC power input (measured at the board's connector, below the shunt) and the VRM output voltage (measured at the output capacitors). It was observed that the fan would pull 12V 1A at maximum speed, and the controller (managing 64 ASICs at 250MHz) consumed 0.34A at 3.3VDC; the maximum additional power draw past board draw, then, is expected to be around 13W. At lower board power consumption, the fan requires much less power; assuming half power for the fan, additional power draw would be around 7W.
I included stable voltage ranges for every 25MHz from 400MHz down to 150MHz, and included the stock setpoint ([email protected]) and the AntMiner S2 stock setpoint ([email protected]) for references. The durations of tests varied, most being between 8 and 20 minutes before sample data was recorded. I tried to run up at least a DiffA of 3000, but sometimes I got distracted and ran more; other times, I got impatient (especially during slow-clock tests) and cut it off at less (typically the 20-minute point). For the first batch of samples (400MHz) I reset the voltage after each dataset was recorded, but did not reboot the device. The calculated error data for each sample at 400MHz is based off the DiffA and HW deltas from the previous sample. For all other samples, the machine was rebooted after setting Vcore.
All measurements were taken on an AntMiner S1 with a build date of 2013/11/18, with a VRM feedback resistor pair R3/R12 of 8200 ohms and 9760 ohms, respectively. All resistor modification calculations are based on this pairing.
GH Expected: Expected gigahashrate for a bank of 8 chips at the setpoint frequency
GH Total: The total expected hashrate for a 64-chip S1 at the setpoint frequency
GH Measured: Reported average hashrate during the measurement period
DiffA: Reported DiffA by the end of the measurement period
HW: Reported HW (hardware errors) by the end of the measurement period
Volts in: DC line voltage into the hashboard, measured at the board terminals
Current in: DC line current into the hashboard, measured across the input shunt (see above)
Power in: DC line power into the hashboard ( Vin*Iin )
Vcore: Measured average VRM output voltage during the sample time
W/GH: The power per measured gigahash-per-second ( Pin/GHM )
HWE Percent: Percentage of hardware errors for the sample period ( HW/[DiffA + HW] )
W/GHE: Watts per expected gigahash-per-second ( Pin/GHE )
Vset: The VRM desired-setpoint voltage, to 0.01V
Replacement R: The resistor value required to replace the VRM feedback resistor (R3, R66, R38, R52), to achieve Vset
Parallel R: The resistor value required in parallel with the VRM feedback resistor, to achieve Vset
| Setpoint MHz | GH Expected | GH Total | GH Measured | DiffA | HW | Volts in | Current in | Power in | Vcore | W/GH | HWE Percent | W/GH Expected | Vset | Replacement R | Parallel R |
| 400 | 25.6 | 204.8 | 25.4 | 4351 | 0 | 11.60 | 3.91 | 45.36 | 1.125 | 1.79 | 0.00% | 1.77 | 1.130 | ||
| 25.5 | 6783 | 1 | 11.61 | 3.81 | 44.23 | 1.112 | 1.73 | 0.04% | 1.73 | 1.110 | 8052 | 446124 | |||
| 25.6 | 9599 | 21 | 11.63 | 3.71 | 43.15 | 1.100 | 1.69 | 0.71% | 1.69 | 1.100 | 7889 | 208238 | |||
| 25.3 | 12927 | 208 | 11.64 | 3.60 | 41.90 | 1.083 | 1.66 | 5.32% | 1.64 | 1.080 | 7564 | 97523 | |||
| 24.9 | 16639 | 581 | 11.65 | 3.51 | 40.89 | 1.068 | 1.64 | 9.13% | 1.60 | 1.070 | 7401 | 75990 | |||
| 375 | 24.0 | 192.0 | 23.8 | 3014 | 0 | 11.65 | 3.49 | 40.66 | 1.110 | 1.71 | 0.00% | 1.69 | 1.110 | 8052 | 446124 |
| 24.3 | 3711 | 0 | 11.66 | 3.41 | 39.76 | 1.088 | 1.64 | 0.00% | 1.66 | 1.090 | 7727 | 133856 | |||
| 24.0 | 3089 | 0 | 11.67 | 3.36 | 39.21 | 1.079 | 1.63 | 0.00% | 1.63 | 1.080 | 7564 | 97523 | |||
| 24.2 | 3327 | 0 | 11.67 | 3.29 | 38.39 | 1.069 | 1.59 | 0.00% | 1.60 | 1.070 | 7401 | 75990 | |||
| 26.6 | 3199 | 0 | 11.68 | 3.23 | 37.73 | 1.060 | 1.42 | 0.00% | 1.57 | 1.060 | 7239 | 61745 | |||
| 24.1 | 3327 | 29 | 11.68 | 3.18 | 37.14 | 1.049 | 1.54 | 0.86% | 1.55 | 1.050 | 7076 | 51622 | |||
| 23.5 | 3071 | 65 | 11.69 | 3.12 | 36.47 | 1.040 | 1.55 | 2.07% | 1.52 | 1.040 | 6913 | 44059 | |||
| 22.9 | 3711 | 212 | 11.70 | 3.04 | 35.57 | 1.029 | 1.55 | 5.40% | 1.48 | 1.030 | 6751 | 38194 | |||
| 350 | 22.4 | 179.2 | 24.4 | 3839 | 0 | 11.71 | 2.97 | 34.78 | 1.049 | 1.43 | 0.00% | 1.55 | 1.050 | 7076 | 51622 |
| 22.9 | 3327 | 0 | 11.71 | 2.92 | 34.19 | 1.040 | 1.49 | 0.00% | 1.53 | 1.040 | 6913 | 44059 | |||
| 22.4 | 3199 | 0 | 11.72 | 2.85 | 33.40 | 1.029 | 1.49 | 0.00% | 1.49 | 1.030 | 6751 | 38194 | |||
| 22.1 | 3327 | 0 | 11.73 | 2.80 | 32.84 | 1.019 | 1.49 | 0.00% | 1.47 | 1.020 | 6588 | 33512 | |||
| 23.8 | 5119 | 0 | 11.73 | 2.75 | 32.26 | 1.009 | 1.36 | 0.00% | 1.44 | 1.010 | 6425 | 29689 | |||
| 22.4 | 3071 | 6 | 11.73 | 2.69 | 31.55 | 0.999 | 1.41 | 0.19% | 1.41 | 1.000 | 6263 | 26508 | |||
| 22.0 | 3071 | 69 | 11.74 | 2.64 | 30.99 | 0.990 | 1.41 | 2.20% | 1.38 | 0.990 | 6100 | 23819 | |||
| 21.5 | 4067 | 229 | 11.75 | 2.58 | 30.32 | 0.979 | 1.41 | 5.33% | 1.35 | 0.980 | 5937 | 21517 | |||
| 22.0 | 4735 | 0 | 11.66 | 3.41 | 39.76 | 1.120 | 1.80 | 0.00% | 1.78 | 1.120 | 8215 | ||||
| 325 | 20.8 | 166.4 | 20.6 | 3583 | 0 | 11.75 | 2.56 | 30.08 | 1.010 | 1.46 | 0.00% | 1.45 | 1.010 | 6425 | 29689 |
| 21.2 | 3071 | 0 | 11.76 | 2.52 | 29.64 | 1.000 | 1.40 | 0.00% | 1.42 | 1.000 | 6263 | 26508 | |||
| 20.8 | 3071 | 0 | 11.76 | 2.46 | 28.93 | 0.989 | 1.39 | 0.00% | 1.39 | 0.990 | 6100 | 23819 | |||
| 21.0 | 3071 | 0 | 11.77 | 2.42 | 28.48 | 0.980 | 1.36 | 0.00% | 1.37 | 0.980 | 5937 | 21517 | |||
| 21.4 | 3071 | 0 | 11.77 | 2.36 | 27.78 | 0.968 | 1.30 | 0.00% | 1.34 | 0.970 | 5775 | 19524 | |||
| 21.2 | 3455 | 0 | 11.78 | 2.32 | 27.33 | 0.960 | 1.29 | 0.00% | 1.31 | 0.960 | 5612 | 17781 | |||
| 20.8 | 3071 | 2 | 11.78 | 2.27 | 26.74 | 0.950 | 1.29 | 0.07% | 1.29 | 0.950 | 5449 | 16245 | |||
| 21.5 | 4863 | 45 | 11.79 | 2.22 | 26.17 | 0.939 | 1.22 | 0.92% | 1.26 | 0.940 | 5287 | 14880 | |||
| 19.8 | 4351 | 172 | 11.79 | 2.17 | 25.58 | 0.928 | 1.29 | 3.80% | 1.23 | 0.930 | 5124 | 13660 | |||
| 300 | 19.2 | 153.6 | 19.0 | 15743 | 0 | 11.80 | 2.11 | 24.90 | 0.951 | 1.31 | 0.00% | 1.30 | 0.950 | 5449 | 16245 |
| 18.7 | 3199 | 0 | 11.81 | 2.05 | 24.21 | 0.938 | 1.29 | 0.00% | 1.26 | 0.940 | 5287 | 14880 | |||
| 19.1 | 3071 | 0 | 11.81 | 2.02 | 23.86 | 0.931 | 1.25 | 0.00% | 1.24 | 0.930 | 5124 | 13660 | |||
| 19.0 | 2687 | 0 | 11.82 | 1.97 | 23.29 | 0.920 | 1.23 | 0.00% | 1.21 | 0.920 | 4961 | 12562 | |||
| 19.2 | 2431 | 0 | 11.82 | 1.92 | 22.69 | 0.909 | 1.18 | 0.00% | 1.18 | 0.910 | 4799 | 11569 | |||
| 18.7 | 2687 | 2 | 11.83 | 1.89 | 22.36 | 0.901 | 1.20 | 0.07% | 1.16 | 0.900 | 4636 | 10666 | |||
| 18.7 | 2687 | 32 | 11.83 | 1.85 | 21.89 | 0.890 | 1.17 | 1.18% | 1.14 | 0.890 | 4473 | 9843 | |||
| 18.2 | 2559 | 121 | 11.84 | 1.81 | 21.43 | 0.881 | 1.18 | 4.51% | 1.12 | 0.880 | 4311 | 9088 | |||
| 275 | 17.6 | 140.8 | 17.4 | 3199 | 0 | 11.86 | 1.67 | 19.81 | 0.880 | 1.14 | 0.00% | 1.13 | 0.880 | 4311 | 9088 |
| 17.7 | 4351 | 0 | 11.86 | 1.63 | 19.33 | 0.870 | 1.09 | 0.00% | 1.10 | 0.870 | 4148 | 8394 | |||
| 17.8 | 4479 | 0 | 11.86 | 1.59 | 18.86 | 0.860 | 1.06 | 0.00% | 1.07 | 0.860 | 3985 | 7754 | |||
| 18.4 | 3455 | 21 | 11.87 | 1.55 | 18.40 | 0.850 | 1.00 | 0.60% | 1.05 | 0.850 | 3823 | 7161 | |||
| 17.0 | 3583 | 110 | 11.87 | 1.52 | 18.04 | 0.841 | 1.06 | 2.98% | 1.03 | 0.840 | 3660 | 6611 | |||
| 250 | 16.0 | 128.0 | 16.2 | 3583 | 0 | 11.89 | 1.39 | 16.53 | 0.840 | 1.02 | 0.00% | 1.03 | 0.840 | 3660 | 6611 |
| 16.4 | 2559 | 0 | 11.89 | 1.36 | 16.17 | 0.830 | 0.99 | 0.00% | 1.01 | 0.830 | 3497 | 6098 | |||
| 16.1 | 3327 | 0 | 11.89 | 1.33 | 15.81 | 0.820 | 0.98 | 0.00% | 0.99 | 0.820 | 3335 | 5620 | |||
| 16.0 | 3071 | 4 | 11.90 | 1.29 | 15.35 | 0.810 | 0.96 | 0.13% | 0.96 | 0.810 | 3172 | 5173 | |||
| 15.2 | 3327 | 46 | 11.90 | 1.26 | 14.99 | 0.802 | 0.99 | 1.36% | 0.94 | 0.800 | 3009 | 4754 | |||
| 15.2 | 3839 | 240 | 11.90 | 1.23 | 14.64 | 0.791 | 0.96 | 5.88% | 0.91 | 0.790 | 2847 | 4360 | |||
| 225 | 14.4 | 115.2 | 14.3 | 3199 | 0 | 11.91 | 1.12 | 13.34 | 0.789 | 0.93 | 0.00% | 0.93 | 0.790 | 2847 | 4360 |
| 15.0 | 2815 | 0 | 11.91 | 1.09 | 12.98 | 0.780 | 0.87 | 0.00% | 0.90 | 0.780 | 2684 | 3990 | |||
| 15.3 | 3071 | 0 | 11.91 | 1.06 | 12.62 | 0.770 | 0.83 | 0.00% | 0.88 | 0.770 | 2521 | 3641 | |||
| 14.3 | 3199 | 56 | 11.92 | 1.03 | 12.28 | 0.759 | 0.86 | 1.72% | 0.85 | 0.760 | 2359 | 3311 | |||
| 15.1 | 3071 | 121 | 11.92 | 1.01 | 12.04 | 0.750 | 0.80 | 3.79% | 0.84 | 0.750 | 2196 | 2999 | |||
| 200 | 12.8 | 102.4 | 12.6 | 3199 | 0 | 11.93 | 0.95 | 11.33 | 0.768 | 0.90 | 0.00% | 0.89 | 0.770 | 2521 | 3641 |
| 12.7 | 4351 | 0 | 11.93 | 0.93 | 11.09 | 0.759 | 0.87 | 0.00% | 0.87 | 0.760 | 2359 | 3311 | |||
| 13.1 | 3967 | 0 | 11.94 | 0.91 | 10.87 | 0.749 | 0.83 | 0.00% | 0.85 | 0.750 | 2196 | 2999 | |||
| 12.5 | 4479 | 0 | 11.94 | 0.88 | 10.51 | 0.739 | 0.84 | 0.00% | 0.82 | 0.740 | 2033 | 2704 | |||
| 14.0 | 3583 | 0 | 11.94 | 0.86 | 10.27 | 0.729 | 0.73 | 0.00% | 0.80 | 0.730 | 1871 | 2424 | |||
| 12.7 | 3583 | 8 | 11.94 | 0.85 | 10.15 | 0.721 | 0.80 | 0.22% | 0.79 | 0.720 | 1708 | 2157 | |||
| 196 | 12.5 | 100.0 | 12.8 | 3199 | 0 | 11.93 | 0.94 | 11.21 | 0.770 | 0.88 | 0.00% | 0.90 | 0.770 | 2521 | 3641 |
| 13.1 | 3199 | 2 | 11.95 | 0.82 | 9.80 | 0.720 | 0.75 | 0.06% | 0.78 | 0.720 | 1708 | 2157 | |||
| 175 | 11.2 | 89.6 | 11.6 | 3071 | 0 | 11.96 | 0.74 | 8.85 | 0.719 | 0.76 | 0.00% | 0.79 | 0.720 | 1708 | 2157 |
| 11.2 | 2559 | 0 | 11.97 | 0.72 | 8.62 | 0.709 | 0.77 | 0.00% | 0.77 | 0.710 | 1545 | 1904 | |||
| 12.1 | 3327 | 1 | 11.97 | 0.70 | 8.38 | 0.697 | 0.69 | 0.03% | 0.75 | 0.700 | 1383 | 1663 | |||
| 9.7 | 3199 | 2 | 11.97 | 0.62 | 7.42 | 0.691 | 0.77 | 0.06% | 0.66 | 0.690 | 1220 | 1433 | |||
| 150 | 9.6 | 76.8 | 9.6 | 3199 | 1 | 11.98 | 0.60 | 7.19 | 0.690 | 0.75 | 0.03% | 0.75 | 0.690 | 1220 | 1433 |
Noteworthy data points:
- 350MHz @ 1.12Vcore, stock S1 setpoint
- 196MHz @ 0.77Vcore, stock S2 setpoint
- 225MHz @ 0.77Vcore, maximum S2 stability point at stock Vcore
- 200MHz @ 0.72Vcore, minimum stability point at 200MHz - some ASICs were unstable below this voltage, causing resets
- 175MHz @ 0.69Vcore, hashrate reports low due to one chip dropping out entirely; remaining 7 hashed well (average 1.39GH, expected 1.20)
- 150MHz @ 0.69Vcore, minimum stable at 150MHz. At 0.68Vcore all chips dropped out and reported 'X' in ASIC status
I currently have a full machine modified for operation at [email protected] (using a 5k6 5% parallel resistor), for which the expected output is 128.0GH at a total power draw (including half-power 6W fan and 1W controller) of about 133W. I measured the power draw at 11.34V 11.52A (using a 1% 0.05ohm shunt; the PSU interface board's 5% shunt measurement reported 11.43A), for 130.6W DC power consumption. The current stats, at 0h 31m 53s operation, are 128.61GH, 59HW, 56191DiffA
This equates to a DC efficiency of 1.02W/GH with a hardware error rate of 0.1%
The fan is reporting 1020RPM, temps 41/43C in a ~65F ambient environment
A note on the maximum S2 stability point at stock Vcore: the S2 uses the same VRM hardware ( 53355DQP monolithic synchronous buck driver ) as in the S1 (and also ASICMiner Cubes and Tubes). Because the S2 is clocked and volt-set to a lower operating point, each ASIC draws far less current than the ASICs in a stock-set S1. The S1 allocates 8 ASICs per VRM; the S2 allocates 16. Therefore, at any particular setpoint on the S1, the power draw per VRM for the same setpoint on the S2 is doubled. If an S1 is stable at 0.77Vcore 225MHz, it is logical to think the S2 would be also. However, the power draw from the S2's VRMs would be twice the 12.62W seen by the S1, at 25.24W. Assuming a 90% efficient regulator (which efficiency typically drops as current increases, due to parasitic resistances in the inductor and drive FETs), that's an estimated output power of 22.72W; as we're outputting 0.77V the current draw is then 29.5A. The 53355DQP is rated for 30A, which means that you're stressing it to 98% capacity continuously. With a best-case efficiency of 95% (and a few other assumptions, to make the comparison easier), the output power is 23.98W, with an output current of 31.1A, a good 3% past rating. With this in mind, it is probably a terrible idea to try and clock an S2 up to 225MHz even if ASIC cooling was adequate.
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