Is NiceHash RandomX hashrate large enough to threaten Monero?
NiceHash’s RandomX hashrate is not, by itself, proof that it can threaten Monero. The key is whether someone could rent enough compatible computing power, control where it mines, and sustain it long enough to overpower honest miners—not simply whether NiceHash lists RandomX.
Compare available power, not just the headline
Hashrate means the amount of mining work computers perform each second. NiceHash is a marketplace where you can buy mining power supplied by other people; it is not one giant mining machine owned by a single operator.
Monero uses RandomX, a mining algorithm designed to favor ordinary computer processors, or CPUs. NiceHash commonly labels its compatible offering “RandomXMonero.”
To judge the threat, you need live figures for:
- Monero’s estimated total network hashrate.
- NiceHash’s currently available, compatible mining power.
- How much of that power a buyer could actually obtain and direct.
Those figures change. Without checking current marketplace data and a Monero explorer—a service that shows blockchain activity—you cannot responsibly conclude that NiceHash is large enough to overpower Monero today.
The majority threshold needs careful math
A “51% attack” means controlling a majority of the mining power working on competing versions of the blockchain, the shared record of transactions. That majority lets an attacker build an alternative history faster on average.
The comparison depends on where the rented power comes from:
- New power added from outside Monero: It would need to exceed the existing honest network’s power to become a majority.
- Power diverted from existing Monero mining: It both strengthens the attacker and weakens honest mining, so the calculation changes.
- A mix of both: You need to separate the two before estimating the attacker’s share.
This is why “NiceHash has half of Monero’s hashrate” would not automatically establish majority control. Marketplace power might also already be included in Monero’s network estimate, so counting it twice gives a misleading result.
A listing is not a guaranteed attack budget
Displayed marketplace capacity does not guarantee that one buyer can obtain all of it at a fixed price.
You also need to consider competing buyers, sellers disconnecting, order limits, connection requirements, and whether the rented miners can be directed to the attacker’s chosen mining endpoint. Taking over existing orders may require paying more.
RandomX makes CPUs competitive, but it does not make rented CPU power harmless. Conversely, the existence of a rental market does not mean a large, sustained attack is practical.
Attack duration matters, too. Monero targets roughly two-minute blocks, but finding blocks is random. A brief hashrate spike is not the same as maintaining control long enough to replace a substantial stretch of transaction history.
What such an attack could actually do
With enough power, an attacker could attempt to reverse their own recent payments, replace recent blocks, or delay transactions. Exchanges and merchants would face particular risk from accepting payments that later disappear from the accepted history.
They could not simply take coins from your wallet, forge your signature, or remove Monero’s privacy protections. Majority mining power also does not let them create arbitrary coins that valid Monero software would accept.
The bottom line
NiceHash is a potential source of attack power, not evidence of an existing threat large enough to overpower Monero. Your useful test is obtainable, controllable, sustained rental power versus the honest mining power remaining. Check live figures, avoid double-counting, and treat claims of guaranteed safety—or guaranteed attack success—with caution.
