Saw a few other posts about how each GPU after the first one takes way longer to pay itself off and was curious so did some rough math myself. The numbers are not exact as it depends on the exact price each GPU you obtain to determine the opportunity cost of using it in the farm but should convey the rough magnitude.
The other posts about this were correct in the general idea that the 1st GPU pays itself off way quicker than every subsequent one, but they seemed to imply each one added more days required before breakeven, which isn't totally correct. Each GPU after the first requires some amount of days to pay itself off, but this happens in parallel. If you add 49 extra GPUs at once, they will all pay themselves off at the same time, not one after another.
Calculations based on the current BTC price of 344276 and the rough value of a GPU. The table below shows how many days of running the farm it takes to pay off a GPU based on whether its the first one or any subsequent one.
|Bought on Flea (800k)||Found in Raid (instead of selling for 800k – 65k fee = 735k)||Not FiR (125k vendor)|
|GPU 1||~2.96 days||~2.72 days||~0.46 days|
|GPU 2-50||~66.9 days||~61.46 days||~10.45 days|
The wiki mentions this as well:
It takes almost 65 days to make the same profit no matter the number of graphics cards, then the higher the number of graphics cards the bigger the profit will be. In this context if the wipe is more then 65 days away it is very important to upgrade the bitcoin farm as soon as possible and get the maximum number of graphics cards afforded at any given time. Only if wipe is sooner then 65 days is it more worthed to not install more then 1 graphics card.
This is totally correct (though the 65 days figure can change based on the cost of GPUs vs BTC)
Based on the table above as a practical example: If you have a bitcoin farm running with 1 GPU and want to buy anywhere from 1 to 49 more GPUs from the flea market to add to it, the farm would then need to run for about 66 days before you catch up to the profit you would have made with just the single GPU, since you need to both recoup all of the money you spent on the GPUs as well as catch up to the profits you would have been making with just the single one during that entire time.
Spreadsheet with the calculations:
Few assumptions/notes to make this as simple as possible:
- Rate of production is based on the wiki formula, which looks correct based on my testing for at least 1-5 GPUs
- The only variables I'm using for the calculations are the vendor sale price of BTC and the price/value of a GPU. GPU price can vary based on whether you bought it on flea, or found it. Finding GPUs and putting them in the farm pays off faster than buying them on the flea market (the difference being caused by the fee you'd have to pay to sell them). Non "Found in Raid" GPUs are worth much less so those are generally worth putting in the farm
- Not taking into account fuel since its negligible
- Not taking into account the cost of upgrading the farm hideout module. This would definitely change the calculation a bit, and make each added GPU past the level 2 and level 3 mark take more time to pay for itself, I just can't be bothered to work out how much as it also depends on the current market prices of every component.