When did Monero adopt RandomX?

Monero adopted RandomX on November 30, 2019, at block 1,978,433. That network upgrade replaced CryptoNight-R, the version of Monero’s earlier mining system in use at the time, and made ordinary computer processors the main focus of Monero mining.

What changed on that date?

RandomX became Monero’s proof-of-work algorithm. That means it became the set of computing tasks miners perform to help secure the network and earn newly issued XMR, Monero’s currency.

The change happened through a hard fork, a scheduled update to the network’s rules. Mining software and the computers checking transactions had to follow those new rules to stay on the upgraded Monero network.

The activation point was a block number rather than a local clock time. A block is a batch of transactions added to Monero’s shared record. Once the network reached block 1,978,433 on November 30, 2019, RandomX became the required mining algorithm.

So, if you see both a date and a block number in an older announcement, they describe the same change.

Why Monero switched to RandomX

The main goal was to make mining harder to dominate with ASICs. These are specialized machines built to perform one particular kind of computing work very efficiently.

Before RandomX, Monero used versions of an algorithm called CryptoNight. Monero had changed that algorithm several times to push back against specialized mining hardware. RandomX took a different approach: it used varied computing tasks and substantial memory requirements to favor general-purpose processors.

Those processors are called CPUs. You already have one in a laptop or desktop computer.

The aim was not to guarantee that every home computer would mine profitably. It was to keep ordinary, widely available hardware useful for mining, rather than give purpose-built machines an overwhelming advantage. RandomX is designed to resist ASIC advantages, not to make specialized hardware impossible forever.

What the switch meant for miners

If you were mining Monero when the upgrade happened, you needed software that supported RandomX. Software configured only for CryptoNight-R could no longer produce valid blocks under the new rules.

The hardware balance also changed:

• CPUs became the preferred choice. RandomX was designed around the work they do well.
• Graphics cards became less competitive. They could run RandomX, but the algorithm did not favor them.
• Memory became especially important. RandomX’s fast mode uses a 2,080 MB dataset, a large collection of working data held in memory.

That last point helps explain why the switch was more than a software name change. RandomX deliberately asks a machine to do work suited to a full-featured computer processor.

The bottom line

The date to remember is November 30, 2019. That is when Monero activated RandomX at block 1,978,433, replacing CryptoNight-R.

If you find a Monero mining guide written before that date, treat its software recommendations and hardware comparisons as historical. For mining today—including in a web browser—you need information that specifically accounts for RandomX. The switch made CPUs more relevant, but it did not make browser mining automatically efficient or profitable.