A CPU can no longer mine Bitcoin cost-effectively. Bitcoin.org's own FAQ says "the only cost-effective method of mining today is using specialized hardware". CPU mining still makes sense for proof-of-work coins built for general-purpose processors, mainly Monero and its RandomX algorithm. For RandomX, the parts that matter most are L3 cache (2 MiB per mining thread), enough fast RAM, hardware AES support and the cost of your electricity. Core count and clock speed come after those.
Why Bitcoin is off the table for CPUs
The Bitcoin FAQ treats CPU mining as history: "In the early days of Bitcoin, anyone could find a new block using their computer's CPU." It now says mining needs specialized hardware and that "there is no guarantee of profit". A desktop processor running Bitcoin's SHA-256 is competing against purpose-built machines. Whatever it earns will not cover the electricity it uses.
Ethereum is no longer an option either. The Merge took place on 15 September 2022 and, according to ethereum.org, "officially deprecat[ed] proof-of-work". Blocks are now proposed by staking validators, not miners.
What the 2022 "CPU" list actually contained
An earlier version of this page listed seven machines as CPU mining computers. None of them was a CPU. They were ASICs, chips built for one algorithm. The specifications below come from third-party listing sites, not manufacturer datasheets:
- Jasminer X4: an Etchash ASIC for Ethereum Classic, listed at 2,500 MH/s and 1,200 W (Kryptex pool guide).
- Goldshell KD6: a Blake2S miner for Kadena, listed at 29.2 TH/s and 2,630 W, released April 2022 (asicminervalue).
- Bitmain Antminer L7: a Scrypt miner for Litecoin and Dogecoin, listed at 9.5 GH/s and 3,425 W, released November 2021 (asicminervalue).
The original prices and "daily profit" figures were dated 16 June 2022. Hardware prices, coin prices and network difficulty have all changed since then, so those figures have been removed. An ASIC cannot be switched to another algorithm. When its coin's economics change, the machine has no other use.
Monero and RandomX: the algorithm built for CPUs
Monero switched to RandomX in a network upgrade on 30 November 2019. RandomX is documented in its GitHub repository, and the 0.15 release announcement on getmonero.org called it the network's "new long-term Proof-of-Work algorithm". The RandomX README describes it as "optimized for general-purpose CPUs". The design document explains the reasoning. CPUs are common and easy to buy, and their instruction sets are well documented. The 2080 MiB dataset is too large for on-chip memory, so specialised hardware has to rely on ordinary external DRAM like everyone else.
Monero's mining page says CPUs are "much more efficient" than GPUs for this algorithm. It describes the algorithm as ASIC-resistant, which keeps mining open to consumer hardware.
What RandomX asks of your hardware
These are the requirements listed in the RandomX README:
| Component | Requirement | Why it matters |
|---|---|---|
| Cache | 16 KiB L1, 256 KiB L2 and 2 MiB L3 per mining thread | Usable threads are often limited by L3 size, not core count |
| RAM | 2080 MiB of shared memory in fast mode; at least 2.5 GiB free RAM per NUMA node | Light mode needs only 256 MiB but "runs significantly slower" |
| Memory channels | Multiple channels recommended | More channels give higher hash rates |
| Instructions | Hardware AES (AES-NI on x86, crypto extensions on ARMv8), 64-bit, IEEE 754 FPU | Without hardware AES, performance falls sharply |
| OS setting | Large memory pages supported | Recommended in the README |
How much the CPU matters: published benchmarks
The RandomX README includes undated reference figures in fast mode with large pages where possible:
| CPU | Memory | Fast mode (H/s) |
|---|---|---|
| Intel Core i9-9900K | 32 GB DDR4-3200 | 5,770 (8 threads) |
| AMD Ryzen 7 1700 | 16 GB DDR4-2666 | 4,100 (8 threads) |
| Intel Core i7-8550U (laptop) | 16 GB DDR4-2400 | 1,700 (4 threads) |
| Intel Core i3-3220 (no hardware AES) | 4 GB DDR3-1333 | 510 (4 threads) |
These are old chips, and the table is useful for comparisons, not as a buying guide. The 8-core chips have 16 threads, but the best results used 8. That fits the 2 MiB L3-per-thread rule. The i3 without hardware AES was more than ten times slower than the i9.
How many RandomX threads can your CPU feed?
Enter your processor's L3 cache and thread count to see roughly how many RandomX mining threads it can run efficiently at 2 MiB of L3 per thread.
| Total L3 cache on your CPU | Hardware threads on your CPU | Rough number of efficient RandomX mining threads |
|---|---|---|
| 16 MiB | 16 threads | 8 threads |
| 8 MiB | 8 threads | 4 threads |
| 32 MiB | 16 threads | 16 threads |
- Cache size and thread count are your own inputs, not figures from any source.
- The 2 MiB of L3 per mining thread is the requirement listed in the RandomX README; the result is a rough guide, not a measured hash rate.
- When the cache allows more threads than the CPU has, the CPU's thread count is the limit.
This only applies the L3-per-thread rule: it does not check RAM, memory channels, hardware AES or large pages, gives no hash rate, and says nothing about electricity costs or whether mining will pay.
How to choose CPU mining hardware
- Check the coin's algorithm first. CPU mining is only worth considering for CPU-oriented algorithms such as RandomX. For SHA-256, Scrypt and Etchash, a CPU cannot compete with ASICs.
- Divide L3 cache by 2 MiB. The result is roughly how many RandomX threads the chip can run efficiently. A chip with more cores but little cache gains nothing from the extra cores.
- Fill the memory channels. Two matched modules on a dual-channel board are better than one larger module.
- Confirm hardware AES and a 64-bit operating system that supports large pages.
- Calculate electricity before revenue. Hash rate per watt and your local tariff decide whether mining covers its costs. The Bitcoin FAQ's warning that there is "no guarantee of profit" applies to every proof-of-work coin.
- Plan for continuous load. A mining CPU runs at full load all day, so cooling and power-supply quality matter more than they do for ordinary desktop use.
Software and how to mine
Monero's mining page says the project "does not endorse any particular pool, software, or hardware". It lists XMRig and CSminer as miners that support Monero and warns that "some miners may have developer fees". XMRig's README describes it as an open-source miner and benchmark for RandomX, KawPow, CryptoNight and GhostRider, with CPU support on x86, ARM and RISC-V.
You have three ways to mine:
- Solo mining with the Monero software is what the project encourages for network robustness. It also warns that solo mining is a "lottery" and "it might take months before you find a block".
- Pools pay out more often but charge a fee. Monero's page also warns that too much hashrate on one pool "is dangerous".
- P2Pool is a peer-to-peer pool in which miners keep "full control over their Monero node". Monero's page says mining with it "is also encouraged".
A recent warning on hashrate concentration
On 12 August 2025, the Qubic project said it had reached 51% of Monero's hashrate and reorganised the chain. Researchers quoted by Cointelegraph disputed that this amounted to a successful 51% attack. On 14 September 2025, The Block reported that nodes saw an alternate chain 18 blocks long. Roughly 117–118 transactions sat on the orphaned branch for almost 40 minutes, and responsibility "has not been established". Anyone mining a RandomX coin should know that a few large hashrate sources can affect confirmation reliability.
Limitations: the benchmarks are undated reference figures from the RandomX README, the ASIC specifications come from third-party listing sites, and this page has no current profitability figures.
