Another New Voltmod Update for the Gridseed 5-chip BTC/LTC ASIC Miners

1 Apr


Today we’ve been experimenting with another alternative voltage modification that has been reported by a reader, the previous mods we have done did require solder bridges and replacement of resistors and the new one relies on a replacement of a single resistor. By replacing the R52 resistor (the resistor on the left of the R52 marking, the actual resistor we are replacing is R139) we can increase the voltage and thus be able to overclock even further the Gridseed ASIC devices, so we did experiment a bit with this modification today.

The default resistor is a 402 type 33 kOhm one and the voltage we have measured across it was 1.1925V. The recommendation we got was to to use a 47 kOhm resistor, so we did just that, after replacing the standard 33 kOhm with a 47 kOhm 402 1% we have measured a new voltage of 1.6885V. This is a significant increase in the voltage that we knew would also lead to significant increase in the total power consumption of the device. The chips might be able to handle even higher voltage and allow for more overclock, however the higher the voltage, the higher the chances are that you will shorten significantly the life of the ASIC device. So if you decide to go for a higher voltage the increase in overclock frequency might get lower and lower, but the total power consumption will continue to increase significantly.


After the voltage modification we were able to get stable performance at 1163 MHz overclock with zero to just a few HW errors per hour which is very acceptable for a local hashrate of about 495 KHS. The poolside results we’ve got with this overclock were about 480 KHS, so very good results in terms of performance after doing this single resistor voltmod. Note that you may have varying results on different miners, some might be able to get up to about 1200 MHz, on others you may need to lower to about 1150 MHz. Regardless of that the performance you can expect to get after doing the 47 kOhm resistor mod is close to 500 KHS or about 100% overclock from the stock 600 MHz and with about 65% performance increase. The expected overclock in Scrypt only mode is about 850 MHz and produces about 360 KHS local hashrate with low to no HW errors. Doing the voltmod can give you about 135 KHS more than what you get with the standard overclock, but also rises the question how much it will increase the power usage.


The total power consumption we have measured with a voltmoded Gridseed ASIC running at 1163 MHz was about 20W (including the fan), so it is pretty much double than what we were getting with the previous voltmods. So the big question is it worth to do this extra high voltage modification in order to get a bit higher hashrate? On the short term it is worth it to be able to squeeze every last bit of performance you can get from the ASIC devices you have in order to get a faster return of investment and on time before the big and powerful ASIC devices start shipping later this year. On the long run however you may significantly shorten the life of the device, we cannot currently say how the significant increase of the voltage may affect the normal operation of the device a few months ahead. So a word of caution, be careful and be aware that this mod may significantly shorten the life of your ASIC hardware. Also going for higher voltage by using higher value resistor may just help you get just a bit more extra KHS, but will surely lead to even more significant increase in the power consumption.

We are going to be giving more extensive testing of the 47 kOhm modification in the following days and reporting the results. Most likely we are going to perform the modification to a few more miners in order to see the variance as well. Also going for 20W total power consumption is Ok for us, but 30-40-50-60W+ with minor extra performance on top is not worth it, though if you wish you could try with a 68 kOhm resistor for example for the maximum overclock, but do proceed with extreme caution as it will increase the voltage and power consumption quite a bit further than with 47 kOhm (voltage regulators may die with too much voltage and over 60W of total power consumption!!!). Do note that playing with voltages is dangerous and can easily lead to damaging your hardware. You should also be very careful with the cooling as you increase the voltage, so do monitor carefully the temperature of the GC3355 chips when you have the cooler disassembled and the unit is working in order for example to measure the voltage. And another word of warning, since 402 resistors are pretty small in size and hard to solder for many people, this mod is not suitable for inexperienced users, so better find somebody that can do it for you if you are not sure you will be able to handle it yourself.

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37 Responses to Another New Voltmod Update for the Gridseed 5-chip BTC/LTC ASIC Miners


April 1st, 2014 at 23:48

Is it an april fool ? :)


April 2nd, 2014 at 00:27

MK, no, it is not a joke – it is real :)


April 2nd, 2014 at 03:50

Can you guys look at the temperature increase during your testing, I am curious if I can still run my fans Quiet (5v) with this mod.


April 2nd, 2014 at 04:08

That is impressive, where’s a good place to buy 47 kOhm 402 1% online?


April 2nd, 2014 at 05:06

You can find them on Ebay.

but If I’m right Admin, we could just use a 47K 1% 1/4w Metal Film resistor right?


April 2nd, 2014 at 07:25


April 2nd, 2014 at 08:50

You state that the power consumption for using the 47k resistor is 20w at 1163 MHz. If you were to run it at a lower frequency, say 1000 MHz, I would assume it will use less power but still remain stable with 0 to minimal hw errors?


April 2nd, 2014 at 11:00

TC, with the 47 kOhm mod you should still be Ok with the fan running a 5V, though we prefer to desolder the fan completely and use external larger fans with slow rpm to cover multiple units with a single fan – lower power usage and better cooling.

finestcuts, yes, the ones from the eBay link should be fine. Just note that you order them locally and not from abroad, these resistors are very cheap anywhere, so no need to wait a lot for delivery. If you can find a local shop where you can pick them up from it is even better.

jamie, yes, metal film resistors should do just fine as well, they are more common and should be easier to find. They should also be a bit easier to solder as well compared to the 402 size SMDs.

Stephen, the power consumption is increased mostly because of the higher voltage, not so much due to the higher clock frequency. Going down to 1000 MHz for example can lower the power usage by something like 1W, so if you are having HW errors or stability issues at 1150, then better lower to 1100 MHz, and not all the way down to 1000.


April 3rd, 2014 at 00:19

Thanks for actually copy pasting without telling sources at all.
Well your source was that thread:

Why dont you name the people who where involved and took some time to acknowledge that ?


April 3rd, 2014 at 00:37

nemercry, if you so much want the source we’ve had it was a reader called jamie who sent us a tip by email on 31.03… and that tip was sent before your “secret” mod was revealed in the topic you cite… furthermore we have already done the mod on our hardware and have published before your mod photos “leaking”. We have not just copy/pasted something, we have actually modified our hardware, tested and confirmed as well as posting our own results. In previous posts about voltmods we have also linked to that topic where the community is working on voltmods…

Mod Scraper

April 3rd, 2014 at 02:12

Hah! I knew it!
I knew nemecry was full of it! And I highly suspect his suggestions to run at even higher clocks than what can be achieved with 47K which he knows will wear out the miner and ruining it fast!
What a plagiarizing little geek!
Glad I caught his cheat and posted his results! He had been telling others he had strung along that he would reveal ‘his’ modification then when pressed to do so, he bulked and said “figure it out yourself!”
Hah! Fixed is ass, good! Robin Hood to the rescue! ;)


April 3rd, 2014 at 22:27

I have a friend that tried to do a few of the mods and wrecked all of the surrounding resistors and now has a pile of these sitting while only one is working!!! Question” where could I find the layout for the PCB and the original resistor falues so I can replace whats missing and messed up in an attempt to recover a few of them?


April 3rd, 2014 at 23:08

didit, the easiest way is to measure the values from another working device, do note that the smaller elements are not only resistors, there are capacitors as well. For schematics for the Gridseed devices you might be able to find some useful information here:


April 4th, 2014 at 00:48

to be honest I don’t know how to measure or check this kind of thing but I can solder my ass off better then most! there is basicly only one that I would need indication of as when he tried to do it he melted the resistor off and couldn’t find it again….. in the original hardware mod where the third position is open and he tried to solder a bridge to it he took out the resistor directly next to it being the fourth one from the top and beside the open to be bridged area on your original hardware mod….. anyone able to help me find out what value that is and where I could find the replacement for it ?
thanks everyone in advance for the info!


April 4th, 2014 at 01:02

didit, if you can write the markings on the PCB for the resistors you need the values of or take a photo and mark them we can measure them and post them here for you.


April 4th, 2014 at 01:15

certainly I can but where should I send the pic to? I cant seem to be able to post one here so not sure where to send it?


April 4th, 2014 at 11:24

Just upload it somewhere and post the link to the photo here in the comments…


April 4th, 2014 at 17:09

I used the picture on the top of this page and made a yellow box with green arrows indicating where and whitch one …


April 5th, 2014 at 12:11


I can confirm that this voltmod is working.

I tried with 57k resistor and it gives me around 540kh/s stable at 1275 mhz with HW errors around 0.5% if cooled enough

I don’t have any watt-meter to check power usage, but it should be around 25-30 watt.

Btw, it isn’t easy to solder. It was the first time I dealt with 402 SMD components.


April 5th, 2014 at 14:43

47-49 kOhm seems to be the optimum choice in terms of hashrate/power usage ratio, going higher does help for smaller increases in hashrate and significant increase in power usage, so you should be extra careful about the cooling. Though they are designed to handle well about 60W, you might be able to go beyond that if for example you try using a 68 kOhm resistor or an even higher value than that.


April 5th, 2014 at 16:31

I find it actually easy to solder these components but whats hard is to try and figure out what components I need? any news from above on what values I would need for my previous post?


April 6th, 2014 at 00:46

Hi didit, according to the BRD file on github, it’s connected to VID1 (pin 13) of the up1509 buck converter.
So when checking the schematic, R333 is the one not connected that needs to be bridged on the first voltmod.
And the one you are looking for should be R332 that is 1k resistor.

Just as a side note, on this new voltmod, we aren’t replacing the R52 resistor (that should be 0 ohm) but the R139 connected to pin 9 of the buck converter and that should be 27k according to the schematic. Anyway, I measured it once unsoldered, and it was 33k.
R52 is the black one just under the circle next to C34 (connected to pin 10) and the next one on the right of the picture is R43 that isn’t connected.


April 6th, 2014 at 01:19

first pictures of the hashrate for 2 miners modded today with 57k resistors.
the second one will run with less errors at 1225 or at 1250 with better cooling (30°C in this room)


April 6th, 2014 at 01:34

Hello! This has been a great blog on OC’ing GS’s. Before I go destroying all my GS’s, my question is…
Is this the ONLY resistor (the R52) that needs replacing to OC? Or is the previous OC method needed in addition to the R52 replacement?
Thanks for any help!!


April 6th, 2014 at 02:03

This is the only one you need to replace.
If you have made the other mods, it’d be better to go back to stock on them.

And even if R52 is written next to it, it’s real name is R139, but it doesn’t matter as long as you physically replace the good one.

56K resistor may use around 40 watt for 530Kh/s
any value between 47k and 52k may have a better hashes/watt ratio.
It seems that 49.9k is one of the best choice.


April 6th, 2014 at 03:08

Jabberwock—–thak you so very much for your input but I am very sorry to say I really don’t understand all that stuff…. is there any way possible that you could send a link “like to ebay or anywhere else would also work” for the piece I need? unfortunately all I know how to do is solder and when I tried looking for the 1k resistor I was unable to find anything that visually looked like it?
this friend is gonna owe me bigtime! I might even get one of these things for myself and try hashing with it?
thank you guys in advance and a LOT!!!!!!!!!!!!!!!!!!!!


April 6th, 2014 at 09:48


April 7th, 2014 at 07:19

Jabberwock Thanks for the reply!!

So here is what I gather so far…

47-57K Ohm 402 resistor is good

So how about the 1% tolerance? Can it be lower, like .25-.5% or does it need breathing room?

Also what Wattage? is 1/4w, 1/2w, more? or less?

Thank You again!!!!!!!!


April 7th, 2014 at 09:08

Hi, AJ,
lower tolerance will be more expensive with no benefit to the performance, but you can use them.

I used 1/16 watt and it’s fine so far, but you can use 1/8 or 1/4 if you have them.
This is the power they can stand without burning.

Be careful with soldering those small pieces.

I find unsoldering easier with soldering iron. then, I apply a little flux on the ne resistor, I put it in place (it will be fine as far as it touches the 2 soldering pads) and then, I use an hot air gun (reflow station) to melt the solder. The resistor puts itself correctly on the pads at this time.

After cooling, don’t forget to clean the flux with isopropyl alcohol and a fine brush. Usually, I even go with a second wash using dishwashing liquid.

There are many “how-to” for SMD soldering, you can just google it if you need more info.


April 8th, 2014 at 07:57

Thanks Jabberwock!
Your replies are much appreciated!!
Sorry, I had to chuckle when you said “lower tolerance will be more expensive” even though their only about $.20 more a piece. But I understand your point :)
I plan to solder these with a low temp solder and flux. I have a adjustable soldering gun with a Fine “small” tip. So with careful hands and tweezers, I’m hoping this will do the trick.
Thanks for the Iso-P tip, never saw that mentioned on any how-to’s for SMD soldering.
Did you have to use new thermo paste when reassembling? I would assume so?


April 8th, 2014 at 16:44

Since they can be cooled almist passively, I’m using the original thermal pad. I also tried replacing them with artic silver ceramic 2 with no visible improvement


April 12th, 2014 at 03:50

Jabberwock, good to know that can still use original paste. Thank You!

sam Roberts

April 14th, 2014 at 00:16

Hi there,

im quite good at soldering, and i know my eletronics. But if you could make a video, or even a before and after picture? or pictures outlining the steps (video would be easiler) it’d be awsome. I might even donate (which is amazing.)


April 14th, 2014 at 00:36

sam Roberts, before and after photos are pointless since you are seeing pretty much the same thing… the first photo in the post is an “after photo”, but since we are replacing a 402 resistor with another 402 resistor with different value the end result looks absolutely the same with maybe some minor difference in the solder joints, but that is really very hard to spot due to the size.


April 20th, 2014 at 18:38

Just to be clear. I have read these comments and admin says he is replacing R52, Jabberwock says he replaced R139. Which is it? If I could get a response from both of you it would be greatly appreciated. Thanks for the information.


April 20th, 2014 at 19:36

blinktoad, you need to replace the resistor marked with the green circle, that is on the left of the R52 marking on the PCB… since R52 is next to the resistor people just assumed this is the marking for that resistor (R52 is actually the empty space below the marking). In fact Jabberwock is probably right that the actual marking of the resistor is R139, it is the one listed as 33K in the parts list in the official documentation. Just make sure you replace the right resistor you see marked on the photo above and you will be fine.


April 23rd, 2014 at 03:25

Just replace R52 or R139. Check my post on
Do that mod ‘only’. It’s ALL you need to do in order to achieve the desired results.
No matter the number designation, everyone who has followed the instructions for R52 has replaced the correct resistor.
No other mods are needed. The later mods are just some squirrels’ attempt to re-invent the wheel! :D
You of course do this mod at your own risk and expense.
Get in touch with me if you need help!
Good luck and enjoy your extra profits!

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