Status as of 1/2022
Prerequisite: What kind of gaming PC is suitable?
Currently mining only makes sense if you already own a not too old (and in case of Nvidia: not too new) graphics card with at least 6GB of dedicated video RAM.
Details
For Nvidia that would mean probably at least a GTX 1060 6GB (2018) or newer. Very new cards of the RTX series are also not very suitable, or at least need a bit of work to get enough performance out of them (they are intentionally limited for mining)
For AMD I don’t have recent experience, might add later. Laptops or graphics integrated in the CPU: 99% forget it. Also: it doesn’t make much sense to buy graphics cards currently, since they recently are extremely overpriced. Also be aware: mining does put some unusual stress on your graphics card, due to typically running 24/7 for many years, while gaming typically is only for a few hours. In this case here we are not going to push any limits (overclocking, …) to get maximum profit whatever the risk, and will also only run for a few weeks or months when it is really cold in Taiwan. This should make it possible to keep the “wear and tear” on the graphics card limited, with no significant risk of early failure. However, the risk is never zero.
Set up first: A way to easily spend or convert to NTD the earned cryptocurrency
For Taiwan the only place useful for small scale mining I found is BitoEX. This Taiwanese company allows you to sell cryptocurrencies for NTD to deposit into your Taiwan bank account, or you can buy gift codes that you can use to pay for things in family mart.
Details
I will add more here later. Generally you need to get verified, which includes sending photos of your ARC, a selfie with ARC (and a photo of your bank book if you want to transfer NTD to your bank account). It takes a few days for this verification. The English website is OK, it just doesn’t explain exactly enough what you need to enter in the “account name” fields (you need the exact same name spelling as on your ARC and bank book respectively). Depositing NTD to your bank account is free, no fees. Family Mart gift coupons have to be printed out using the self service station in the store. The rules say you can’t buy tobacco or alcohol with it, but at least when I tried it, it worked ok to pay for beer.
Next step: find a mining pool
The are only two mining pools that seem useful for very small scale Ethereum mining: Nicehash is easiest for beginners to set up, but can only withdraw every ~1200 NTD (0.0005 BTC). 2miners is a slight bit more profitable and can withdraw every ~500 NTD (0.005 ETH) - so I chose 2miners.
Details
I will add more here later. Currently it seems only Ethereum mining is meaningful (This will change soon). For people with just one or two graphics cards most mining pools have huge problems, though: First it takes a long time of mining, maybe several weeks, to reach the payout threshold. And then the transfer fees take away lots of the earnings. These two pools work around this issue by not paying directly in Ethereum, but in Bitcoin. This means that for 2miners, if you choose to get paid in Bitcoin you get paid every 0.005 ETH = roughly 500 NTD (with 2 graphics cards I need around a week for that), and the transfer fees are small (maybe 5 NTD).
Setting up the PC for mining
You need to download a mining program and set it up to use your mining pool and your BitoEX bitcoin wallet address.
Details
I will add more here later. For Nvidia cards I use Gminer. For certain old high-end cards with GDDR5X memory (RTX 1080 and 1080Ti) it can make sense to use T-Rex or some other miners instead, since they have a special memory optimization that can extremely boost performance on those two card types. For the newest RTX cards with mining limiting (LHR) different mining software continuously improves workarounds, so it would need some experimenting to find a good setup.
Optimizing the mining PC
Optimize the PC for a good balance of performance, power draw, cooling and loudness.
Details
I will add more here later. Basically, many Nvidia cards like my GTX 1660s use way too much power with default settings. You can limit them to for example 60% of their maximum power without any noticeable drop in mining performance. Depending on the mining program you can limit directly through the mining program, or use a 3rd party app like MSI Afterburner
I will add more details here. But in case anyone wants help setting up: I am in no way a professional, but I dabbled into mining for around a decade and successfully helped several people setting up and optimizing small GPU farms.