RandomX v2: what changes and when Monero switches

RandomX v2 is the first change to the algorithm itself since Monero adopted it in 2019. It was merged into the reference code on 17 February 2026 and released as RandomX 2.0 on 25 March 2026. It is not a new algorithm: the cache, the dataset and the scratchpad are the sizes they were, and in the specification's table of parameters the program size is the only one that differs between v1 and v2. What changes is how much work one hash does with them.

The four changes

Longer programs. Each of the eight programs in a hash grows from 256 instructions to 384. The design note gives the reason: processors have become much faster since 2019 and memory has not. A Ryzen 9 9950X is more than 1.5 times as fast as the 2019 Ryzen 9 3950X in most benchmarks, but only 20 to 25% faster in RandomX, because both wait about 50 to 55 nanoseconds for a line from memory. Longer programs give a fast core something to do while it waits.

AES in the main loop. The two groups of floating-point registers are now mixed with AES rather than XOR, which doubles the AES work per hash. The note says this fills a gap where the processor sat idle waiting for the scratchpad, so it costs little — and that it means specialised hardware has to build AES into the virtual machine itself, not only into the step that fills the scratchpad.

A rarer rounding change. In v1 the CFROUND instruction changes the floating-point rounding mode on every loop. x86 processors were not built for that, and the note puts its cost at up to 10% of hashrate on Ryzen — an easy advantage for a chip that was. In v2 it changes the mode only about one time in sixteen.

A deeper prefetch. The dataset is read two loops ahead instead of one, which goes with the longer programs: more time between asking for a line and needing it.

What it costs per hash

The pull request counts the work. A v1 hash is 4,194,304 virtual-machine instructions and 262,144 AES operations, 4,456,448 in all; a v2 hash is 6,291,456 instructions and 524,288 AES operations, 6,815,744 in all — 52.9% more.

The hashrate falls by much less than that, and on some machines it rises. In the design note's own tests a Ryzen 9 9950X at 285 W went from 27,186 to 26,792 hashes a second, 98.6% of its v1 speed, while doing 50.7% more work per joule. A Ryzen 7 3700X kept 85.4% of its speed and an Intel Core i7-8650U at 15 W kept 77.3%; a Ryzen AI 9 HX 370 at 28 W got faster, at 108%. The design note's point is efficiency: on every machine it tested, the work done per joule went up, by between 16% and 67%.

When Monero switches

Not yet. As of 25 October 2026 Monero still runs v1. The change to Monero itself is pull request 10038, "support RandomX V2 and commitments in v17", opened in August 2025 and still open, last updated in mid-October 2026. As its title says, it is planned for protocol version 17, which means a hard fork, and no date has been set. Monero's last network upgrade was on 13 August 2022, at block 2,688,888.

The software is ready ahead of the network. XMRig added RandomX v2 in version 6.26.0 on 28 March 2026, under the algorithm name rx/2. P2Pool's v5.0 beta of 1 October 2026 lists RandomX v2 support among its new features, but it runs only on the beta stress network for FCMP++ and Carrot, Monero's planned privacy upgrade, and refuses to run on the main P2Pool chains.

Until the fork, mining Monero means mining rx/0, and a miner set to rx/2 would produce hashes the network rejects. The XMRig guide has how a miner is told which one to run.