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Antminer U1 mod & tune up

I have one “bad” Antminer U1. Well… bad… at stock Freq it runs fine, when I tune it to 0981 it has about 30% hardware errors. Time for some research and tune up. I took off the cooling plate with the antminer logo. There is no cooling pasta between the plate and the PCB but some kind grey rubber something. Must be conducting too I guess but threw it away. First I wanted to fit a huge CPU cooler from an old Dell PC but it’s a little overkill. I had an alumium heatsink, cut a bit off with a saw. Drilled two holes in it for the screws. Applied some thermal paste, fitted the heatsink and tightened the screw. Applied the Antminer cooling plate just for the looks.

Plugged the Antminer U1 straight into an USB port. Installed a simple USB fan for a little extra cooling. Installed bfgminer 3.10.0 and ran it with several options:

./bfgminer -o YOUR POOL URL -u WORKERNAME -p WORKER PASSWORD -S antminer:all --set-device antminer:clock=x0A81 --icarus-options 115200:2:2

It hashes between 2.10 and 2.20 GH/s. Sometimes it peaks to 2.35.

When I leave out the –icarus-options

./bfgminer -o YOUR POOL URL -u WORKERNAME -p WORKER PASSWORD -S antminer:all --set-device antminer:clock=x0A81

hashing never gets higher than 1.98 max 2 GH/s, so in some way it needs the –icarus-optoins 115200:2:2

By the way, the 30% hardware errors are gone. Could it be the new heatsink? or is BFGminer better than the modified CGminer?

The extra fan isn’t really necessary, with the heatsink it doesn’t get hot or overheated. The Antminer U1 draws 0.34 Ampere and 5.03 Volt from the USBport.

Without modification to the hardware I didn’t get above 2.2 GH/s avarage (some peaks to 2.35 of 2.4 GH/s) no matter what Frequency Hex I used above x0A81. When you use hight values than 0A81 , hashingpower stays at 2.2GH/s but the powerdraw raises and also heat ! with option 4C81, 325 MHz, power draw is 0.6A ! Hashrate stays at 2.2GH/s

Freqency (MHz)
ASIC hash rate (GHz)
Frequency Hex

























Link to official Antminer Manual:Β https://github.com/AntMiner/AntGen1/blob/master/manual/AntMiner-U1%20user%20guide.pdf?raw=true

Next step is to modify the hardware and replace or add extar resistors. R1 and R2, see page 4 of the Antminer manual


DC/DC output


















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  1. Nice article, im following! I also ordered a few heatsinks for extra cooling them. Going to try overclock them too if you get good results with it.

  2. I actually changed the resistors:
    This gives according to the datasheet of the dc-dc converter a Vout of 1.18 Volts.
    It’s too bad the manual is talking about hashrates of 2.2, but that’s nearly always impossible without changing the voltage.
    And as their list with rates goes up to 4, they might have considered their layout better, almost all components around the chip are taller, thus making the possibility of adding an extra heatshield much more difficult, cooling from just the rear of the PCB is not enough.
    Picture of how mine sort of looks like

    • thanks for your comment. Picture looks great, but didn’t you get a higher hashrate at 1.18V ? I guess it should hash above 2.8 GH/s

      • Hashrate can get higher, but cooling is the problem. The chip needs better cooling from topside.
        Also the coil is getting hot, which is a serious problem, as that one isn’t easily cooled. Have to look why it gets hot, it shouldn’t.

        • First testrun at x4D81 wasn’t very impressing..
          bfgminer version 3.10.0 – Started: [2014-01-20 22:24:50] – [ 0 days 00:34:38]
          Connected to xx diff 1 with stratum as user xx
          Block: …adc497ce #281570 Diff:1.79G (12.81Ph/s) Started: [22:48:58]
          ST:2 F:0 NB:3 AS:0 BW:[ 48/ 29 B/s] E:13.36 I:25.52uBTC/hr BS:278
          1 | 1.73/ 2.26/ 2.18Gh/s | A:477 R:0+0(none) HW:2/.19%

          Worse than x4C81. Will let it run through the night and hopefully better results an is it stil alive πŸ˜‰
          Too bad the chip doesn’t have a temperature sensor, at least, nog that I know of.

          • Okay, Now the results are better:

            bfgminer version 3.10.0 – Started: [2014-01-20 23:00:37] – [ 0 days 10:27:13]
            Connected to pool diff 2 with stratum as user zwemmer
            Block: …3e0fd7ea #281646 Diff:1.79G (12.81Ph/s) Started: [09:26:15]
            ST:2 F:0 NB:77 AS:0 BW:[ 50/ 39 B/s] E:14.62 I:32.39uBTC/hr BS:26.8k
            1 | 2.52/ 2.37/ 2.78Gh/s | A:12054 R:36+0(.30%) HW:0/none

            But also the dc-dc converter is getting hot. Fortunately that one has an over temperature protection.

          • Can you possibly tell me which Freq Hex you used to get 2.52/ 2.37/ 2.78Gh/s?

        • The reason why it gets hot is becouse the vreg is rated for 3amps max at 1.18v your already above the limit, hence it gets hot. here is the datasheet on the vreghttp://www.aosmd.com/pdfs/datasheet/aoz1021ai.pdf

          gonna see if i can find a replacement for it here at work(im a ee)and i need to contact bitmain as they have given out diffrent specs compared to the datasheet on BM1380 chip + they should be able to run higher clocks as they are used in the antminer S1 if im not mistaken, and its 32 chips running around 90Gh/s and thats 2.8Gh/s per chip so i just need to know what vreg they used for the chips on the s1 boards and see if i can mod the u1.

          • I already had the datasheet πŸ˜‰ I only wasn’t able to measure the current.
            But indeed, the configuration is wrong, as the Antminer U1 speaks of 1.2 volts, which it shouldn’t if it then would draw too much current (and thus probably also saturates the coil, and probably that’s the reason the coil also warms up.
            So actually you can only go up to about 1.0 Volts and then hope you chip will be stable at high frequencies.

          • Can’t edit the reply so then a extra one.
            Thanks for pointing me to the datasheet of the BM1380, didn’t think of that. Now it at least explains why the coil and converter are getting hot πŸ˜‰

            Would be nice to find a cheap pin compatible replacement, but that’s probably not gonna happen.

  3. Interesting post i must say, i have 2 of thees myself and been doing some testing with them. Iv been using 2 diffrent kinds of software to test them. Bitminter client with the silabs drivers, this will dish out alot of errors before starting up and running at stable 1,5Gh/s per miner, hw was about 10% after 24houres of testing. With the cgminer v3.8.5 for antminer i tryed running at diffrent speeds, but one noticable thing is running them at 0981 was the “sweet spot” they run 1,9-2,1Gh/s stable and they only had 0.5% hw in 24houres run, every other config would make them put out more hw and running unstable, everything above 0A81 wouldent work at standard voltage(they wouldent start up) I have just changed the resistors and will be running both at 1.06v to see if i can push them higher and if the hw drops but thats for when i get home from work this afternoon. One more thing i noticed is im run a i7-4930k so iv been using it to mine with too (not btc tho) when i was running all 12 cores i had a preformance impact on about 50% on my cgminer!!! so make sure you have at least 5-10% cpu power left for bfg/cgminer to make sure it runs smoothly.

    • Thanks for your great comment, very useful for all miners. Are you mining XPM with the i7?

      • i was mining XPM to start with but went for YAC insted untill the diff is too high for my few pc`s then ill be switching back XPM cpu mining, im running 11 threads YAC minning, the last thread is to ensure that cgminer and cudaminer runs smoothly.

  4. Here are some of my results after roughly 17hrs of mining, with setting 4C81 2,6Gh/s and 1,06V

    cgminer version 3.8.5 – Started: [2014-01-21 22:43:49]
    (5s):4.870G (avg):4.501Gh/s | A:69524 R:42 HW:271 WU:62.6/m
    ST: 2 SS: 19 NB: 152 LW: 115104 GF: 2 RF: 0
    Connected to mint.bitminter.com diff 4 with stratum as user testant_1
    Block: fe5c3ebf… Diff:1.79G Started: [17:08:08] Best share: 5.78M
    [P]ool management [S]ettings [D]isplay options [Q]uit
    AMU 0: | 3.757G/2.248Gh/s | A:34986 R:18 HW:145 WU: 31.3/m
    AMU 1: | 1.421G/2.255Gh/s | A:34542 R:24 HW:126 WU: 31.4/m

    4,5Gh/s and too many HW for what my goal is with thees 2 miners. Iv looked for a replacement for the AOZ1021 but havent been able to find a “drop in” replacement for it. The closest is AOZ1094AIL rated for 5A but circuit change is needed, ill slaughter one of my miners and see if i can get it working sometime next week when parts arrive. My goal is 5Gh/s for both with minimal HW and hopefully ill reach it πŸ˜€

  5. Hi there,

    I have just ordered one of these AntMiner U1’s from amazon. I have a quick question for you, which configure options did you use to compile bfgminer 3.10.0?

    Kind Regards,


  6. I can confirm that I now have it all up and running.

    I originally thought you needed to enable the specific device driver at compile time, but it seems that you don’t.

    Thank you again for clarifying this for me,

    Kind Regards,


  7. @DESTINY (cannot replay)
    I don’t know exactly, but now both miners run at X4E81
    The one which drars a bit too much current for the converter (however, the converter has overtemperature & overcurent protection):
    AMU 0: | 2.61/ 2.45/ 2.94Gh/s | A:564 R:5+0(.88%) HW:1/.06%

    The other miner I used:
    R1 = 12k
    R2 = 39K
    Which gives a voltage of about 1.046, and a current probably a bit less than 3A.
    It runs fine, but with much more errors:
    AMU 0: | 2.38/ 2.44/ 2.88Gh/s | A:3018 R:6+0(.18%) HW:92/1.2%

    • Hi, I am from Australia and I sell miners, I am experimenting to put the miners in oil for cooling, running stable at 2.0G but unable to push it any further. I dont have much experience in electronics but I would like to give it a try, could you let me know which two resistors I should get and what else I need to run them at higher speed? Thanks

      • Hi, overclocking a Antminer U1 should be an experiment or a sport πŸ™‚ When you want it for more hashpower and want to use the overclock for more antminers (say 10+) you better think about buying a miner with more hashpower rather than overclocking the Ants. with overclocking the miner becomes unstable, uses more power, generates more heat and the costs for overclocking won’t give more cryptocoins than you invest in tuning them. Just a tip.

  8. Pingback: PC Onderdelen Bitmain AntMiner U1 -- 1.6GH/s - USB Bitcoin ASIC Miner Block Erupter

  9. I was looking for something on github when i came across this. https://github.com/AntMiner/AntGen1/tree/df086b5d1b5576701362393a0b4a198e7c2dfc48/cgminer

    Seems like the frequency code for 325, 350, 375 and 400Mhz are “wrong” compared to what they give out in the pdf file for antminer u1, just a headsup for you miners if your having trouble with your ants around that area of Mhz.

  10. In your picture of the antminer you have R1 outlined in RED an R2 outlined in GREEN but the Antminer User Guide shows them opposite what you have listed. Which image show the correct location of the resistors? Thanks!

    • oops I switched R1 and R2 πŸ™ Manual is correct, I will fix my photo tomorrow. Thanks for the reply

      • No problem, I figured as much since the datasheet for the power IC explains the usage of the voltage divider on the feedback pin and the mention of the fixed value and the variable value resistors matched the Antminer Guide. Of course someone using them backwards could put as much as 5v on the output and that’s probably not a good thing :). BTW: Thanks for the guide you put out here!

  11. You’ll get too many HW errors if you go much of 2Gh/s.
    HW is bad…ANY HW is bad.
    Great tip on the –icarus-options 115200:2:2.
    AFAIK it’s a necessary parameter.

    • I have run 20 Ant U1s without the icarus parameter. Just –set-device antminer:clock=x0981. Once i added “–icarus-options 115200:2:2 –icarus-timing 3.0=100”
      my rejection rate went through the roof.

      as I don’t understand what the option does, I won’t even guess as to the cause. Could be lack of power, multipool issues, running redfury and icefury devices at the same time as the ant U1…no clue.

      if anyone has an ELI5 of the icarus setting when used with BFG 3.10.0….I’d appreciate it.

      • this should give you zero issues but you dont even need it as the devices will only max out and run stabe at 1.98 – 2.0
        –icarus-timing 2.5=90

  12. Cooling will not be an issue. Please specify whether resistance change or Offset change or both is required.
    Thank you

  13. I am getting 2.1 to 2.2Gh/s running at 0A81 on the U1 miner and using a stock intel CPU cooler /w fan.

    I had the cooler that came with an old i7 3800 CPU I bought (the cooler is not adequate for the i7 CPU, but it keeps the AntMiner nice and cool!).

    I can not run cgminer with any speed faster than 0A81, it just spins with frequency mismatches at 0B81 or higher…

    I am going to try a couple U2 miners while the difficulty is still low enough to mostly make back the investment if BTC stays above $500/BC.

    I recommend using a USB extension and the cheap $5 CPU cooler since the thermal paste is enough to bind the U1 to the CPU cooler and the miner stays cool to touch.
    I can post pics if anyone want to see.

  14. Could I use those commands in MinePeon?

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