What would happen if Bitcoin Mining algorithm changed to GPU and CPU only?

[PrivacyG]

Mining Farms gaining more and more percentage of the total hashing power is an often discussed subject here.  My theory is that in the event of an already large Miner gaining enough control of the Mining that a 51 percent attack becomes more likely and easy to accomplish than we would expect and like, Bitcoin would have to suffer a Hard Fork which would expel any sort of equipment other than CPUs and GPUs so the power could be redistributed among the community instead of a majority of it being distributed among few giant Miners.

I do not know how much of a solution or how feasible this would be.  But say this was a thing and Bitcoin became GPU and CPU mineable ONLY like it used to be many years ago.

What would happen?  What are the risks we would run into?

[m2017]

Mining Farms gaining more and more percentage of the total hashing power is an often discussed subject here.  My theory is that in the event of an already large Miner gaining enough control of the Mining that a 51 percent attack becomes more likely and easy to accomplish than we would expect and like, Bitcoin would have to suffer a Hard Fork which would expel any sort of equipment other than CPUs and GPUs so the power could be redistributed among the community instead of a majority of it being distributed among few giant Miners.

I do not know how much of a solution or how feasible this would be.  But say this was a thing and Bitcoin became GPU and CPU mineable ONLY like it used to be many years ago.

What would happen?  What are the risks we would run into?

With the risk of an increase in the price of the GPU and CPU upon sale. This has already happened several times with the GPU - during the rise in the price of cryptocurrencies, like ETH. A sharp increase in demand for GPU and CPU will create a shortage and an increase in cost.

From the point of view of decentralization, mining on CPUs and GPUs would be preferable, which would allow even ordinary users, just with a regular PC, to be part of the BTC-system and receive their small commissions from this.

The question is, how can it be technically possible to make ASICs impossible to use? It seems to me that it is no longer possible to go back to the old ways and simply abandon mining farms.

[Venik]

It's almost impossible to mine BTC on GPUs nowadays. I mean, it's possible, but computing power is not enough, and miners won't get any profits, the mining is too slow and expensive.

[franky1]

anything a CPU can do a asic can do better

even if mining changed to a 11 algo technique. ASICS can just have 11 varieties of chips each performing each algo and end up doing more hashes than a CPU/GPU

the only reason many of the multi algo mining methods altcoins dont have asics is because they are crapcoins so no one cares to design asic chips to mine those crap coins
its not a techical problem, its a lack of interest problem

..
end result if bitcoin changed algo is:
if the difficulty the day before algo changed stayed at todays asic rated difficulty number and had to step down periodically
the network would have needed many years of not solving blocks due to how long one cpu would take to solve a block at current difficulty

it would take years for a CPU to solve 1 block let alone get 2016 blocks to then trigger a difficulty step down.. and then still years to step down enough to then be cpu attainable mining...

but within that time if the community had not abandoned bitcoin already. smarter minds would have made an asic to out achieve solo mining CPU. so you wont see thousands of solomining users winning blocks per month..

if as part of the algo change they used a CPU level difficulty start point on D-Day
users would already be trying to pool multiple CPU/GPU

and within days solo mining is gone again..
and if bitcoins market, utility has not already been lost due to this silly idea.. smarter minds would ahve designed asics to outperform GPU
and we would be back to ASIC farming again and the silly idea would have been a waste of a couple years of annoyance.. for ultimately nothing

[pooya87]

I do not know how much of a solution or how feasible this would be.  But say this was a thing and Bitcoin became GPU and CPU mineable ONLY like it used to be many years ago.

That is impossible because we are talking about computation, and you can not force what hardware is used to perform that computation. In other words any algorithm can have a more efficient hardware including ASICs that performs the required computation.
This is why there has never been such thing as "ASIC resistant" algorithm despite many altcoins creating algorithms that they call "ASIC resistant" starting from the oldest one LTC and the most hyped shitcoin called ETH both of which ended up having ASICs built for them.

As for your concern, you have to remember that we are talking about mining pools not miners having 51% of hashrate. Pools don't own hashrate, the miners do which means they can switch to another pool and this has happened in the past like the case with GHASH.io.
Another better solution to solve this is to change the pool algorithm (not Bitcoin's mining algorithm) so that the miners connecting to the pool have a control over what they mine so that the pool can't perform any attacks, vote for or refuse to vote for new proposals, etc.