<p>Just adjusting the nonce is not sufficient for mining a valid Bitcoin block at the current difficulty level which is around <a href="https://www.blockchain.com/en/charts/hash-rate" rel="nofollow noreferrer">80 exa-hashes</a> (80 x 10<sup>18</sup> hashes) per second. Nonce field in the block is only 4 bytes which means it can at most provide you 2^32 different hashes(4.2x10<sup>9</sup> hashes). That is the reason, miners adjust the extra nonce value in the coinbase transaction and then iterate over the entire 2<sup>32</sup> nonce field again.</p>

<p>Supercomputers are way slower than ASICs for mining purposes. Supercomputers contain huge CPU power that are highly useful for general purpose computing however, for running a particular task they will be much slower compared to a hardware that is designed specifically for that purpose. That is the reason miners use ASICs where the <code>dsha256</code> algorithm is printed on the circuit in the hardware. These chips can't do anything else, but run the double SHA256 hashes which provides them advantage over even a supercomputer.</p>

<p>Miners generally run another machine connected to these ASICs chips. While the ASIC chip is exhausting the nonce space, the other machine changes the extra nonce value and queues it up for the ASIC hardware to take it from there. So these task can be run in parallel.</p>

CC BY-SA 4.0
2019-08-26T14:13:20.353Z
2019-08-26T14:13:20.353Z
Ugam Kamat
<p>Because each miner may select the transactions (and the order in which they are included) in each block. Also, they do not all start on the same exact nonce, in fact they are changing more than just the nonce in many cases (e.g. block versions - see <a href="https://www.asicboost.com/" rel="noreferrer">ASIC BOOST</a>).</p>

<p>This means that they are not all performing the HASH256 (proof of work algorithm) on the exact same data, so the outcome is random. However, more powerful computers can perform more hashes per second, so they will find a solution on average, more often than a less powerful computer. These computers, by the way, are specialized hardware called miners, not general purpose computers.</p>

CC BY-SA 4.0
2019-08-26T14:13:37.887Z
You beat me to punch ;)
Ugam Kamat
CC BY-SA 4.0
2019-08-26T14:14:39.680Z
haha sorry @Ugam :)
JBaczuk
CC BY-SA 4.0
2019-08-26T22:36:32.220Z
Note that it's not just POSSIBLE but actually NECESSARY for each miner to include different transactions, because one of them -- the coinbase transaction -- is how the miner gets paid for mining, and has to contain the miner's payment address.
Glenn Willen
CC BY-SA 4.0
2019-08-27T14:12:01.220Z
And aside from this, even if multiple hashers would work together on the same nonce, they are essentially trying to get lucky in guessing a value which will hash to the requested prefix. - if all start guessing at 0000... and incrementing from there, they would all be trying the same numbers and the fastest one would win every time. But you can start guessing anywhere - theoretically you could randomly start guessing anywhere and get lucky every time on the first try and beat all the super-computers with your lone PC.
Falco
CC BY-SA 4.0
2019-08-26T14:11:22.743Z
2019-08-26T14:11:22.743Z
JBaczuk
<p>I just read about how miners have to change the nonce bit in order to find an hash below a certain result.</p>

<p>Granted each miner process it the same way, incrementally, adding 1 and hashing, adding one and hashing, what prevents the most powerful computer on the network to snatch all rewards?</p>

<p>I feel like beside the moment each miner starts mining a block, there's no room for luck and a lesser powerful machine, to ever add a block. </p>

<mining-theory><proof-of-work>
Why is the winner of Pow different everytime?
Sebastien FERRAND
# Why is the winner of Pow different everytime?

(Asked by: username_0 on 2019-08-26)

I just read about how miners have to change the nonce bit in order to find an hash below a certain result.

Granted each miner process it the same way, incrementally, adding 1 and hashing, adding one and hashing, what prevents the most powerful computer on the network to snatch all rewards?

I feel like beside the moment each miner starts mining a block, there's no room for luck and a lesser powerful machine, to ever add a block.

**Tags:** mining-theory, proof-of-work


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## 2 answers

### Answer by username_2 on 2019-08-26. Score: 10 | Accepted answer

Because each miner may select the transactions (and the order in which they are included) in each block. Also, they do not all start on the same exact nonce, in fact they are changing more than just the nonce in many cases (e.g. block versions - see [ASIC BOOST](https://www.asicboost.com/)).

This means that they are not all performing the HASH256 (proof of work algorithm) on the exact same data, so the outcome is random. However, more powerful computers can perform more hashes per second, so they will find a solution on average, more often than a less powerful computer. These computers, by the way, are specialized hardware called miners, not general purpose computers.

> **Comments:**
> **username_1**: You beat me to punch ;)  
> **username_2**: haha sorry @username_1 :)  
> **username_3**: Note that it's not just POSSIBLE but actually NECESSARY for each miner to include different transactions, because one of them -- the coinbase transaction -- is how the miner gets paid for mining, and has to contain the miner's payment address.  
> **username_4**: And aside from this, even if multiple hashers would work together on the same nonce, they are essentially trying to get lucky in guessing a value which will hash to the requested prefix. - if all start guessing at 0000... and incrementing from there, they would all be trying the same numbers and the fastest one would win every time. But you can start guessing anywhere - theoretically you could randomly start guessing anywhere and get lucky every time on the first try and beat all the super-computers with your lone PC.  

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### Answer by username_1 on 2019-08-26. Score: 3

Just adjusting the nonce is not sufficient for mining a valid Bitcoin block at the current difficulty level which is around [80 exa-hashes](https://www.blockchain.com/en/charts/hash-rate) (80 x 1018 hashes) per second. Nonce field in the block is only 4 bytes which means it can at most provide you 2^32 different hashes(4.2x109 hashes). That is the reason, miners adjust the extra nonce value in the coinbase transaction and then iterate over the entire 232 nonce field again.

Supercomputers are way slower than ASICs for mining purposes. Supercomputers contain huge CPU power that are highly useful for general purpose computing however, for running a particular task they will be much slower compared to a hardware that is designed specifically for that purpose. That is the reason miners use ASICs where the `dsha256` algorithm is printed on the circuit in the hardware. These chips can't do anything else, but run the double SHA256 hashes which provides them advantage over even a supercomputer.

Miners generally run another machine connected to these ASICs chips. While the ASIC chip is exhausting the nonce space, the other machine changes the extra nonce value and queues it up for the ASIC hardware to take it from there. So these task can be run in parallel.


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