One of Lee’s initial claims has not held up, however: the ability to mine litecoin using a computer’s central processing unit (CPU). Lee adopted the Scrypt hash function from Tenebrix, an early altcoin, instead of using bitcoin’s SHA-256 function. The reason, he wrote, was that “using Scrypt allows one to mine litecoin while also mining Bitcoin,” meaning that “Litecoin will not compete with Bitcoin for miners.” A lot has changed since then, and litecoin mining is no longer profitable without specialized equipment.
In the early days, even bitcoin could be mined using a CPU. By 2011, the competition had ramped up, and the only way to mine bitcoin profitably was using a graphics processing unit (GPU). By choosing Scrypt, Lee allowed litecoin to be mined on CPUs, but that didn’t last long either. Soon GPUs were being used to mine litecoin as well. Then application-specific integrated circuits (ASICs) were developed to run SHA-256, and bitcoin miners moved away from GPUs.
Lee said in March 2017 that this transition partly explains his creation’s success: litecoin “got lucky where, when bitcoin mining went from GPUs to ASIC, all the bitcoin GPUs were looking for a coin to mine, and litecoin just happened to have transitioned from CPU to GPU at that time.” Soon enough, however, ASICs were developed for Scrypt, and today it would be difficult if not impossible to turn a profit using anything but ASICs. One popular ASIC for Scrypt mining is Bitmain’s Antminer L3+, but batches tend to sell out almost immediately, meaning you have to watch Twitter like a hawk; the company only accepts bitcoin cash and USD wire transfers (for some batches it only takes the former). Innosilicon is accepting pre-orders for a competitor, the A4+ LTCMaster. Other options are available, but the newest ASICs tend to run at least $2,000 and sell out quickly. Older ASICs may not be competitive, making it hard to turn a profit.
Note that Scrypt ASICs can also be used to mine other coins based on the same algorithm; you can choose the most profitable coin to mine based on relative price and difficulty (a parameter the network sets to make sure a new block is mined every 2.5 minutes on average, whatever the total hash power).
As long as you’re aware that you won’t make money, you might have your reasons for mining with a CPU or GPU. It’s a way to get exposure to the process, to familiarize yourself with the vocabulary and concepts, and to avoid dropping thousands of dollars on a pursuit you find out doesn’t interested you.
And if you’re an altruist, offering your tiny sliver of hash-power to the network is a way to reduce its centralization. “Centralized mining is pretty bad for bitcoin and litecoin,” Lee says, “because mining is supposed to be anonymous, where you don’t know who the miners are, and they’re all individually acting selfishly to make the money, which indirectly makes the coin secure.” On the other hand, a laptop’s worth of hash power won’t make a dent in the big miners’ market share, and you’re likely to inflict wear and tear on your equipment.