Why does XMRig say "failed to apply MSR mod, hashrate will be low"?

XMRig shows “failed to apply MSR mod, hashrate will be low” when it cannot change certain low-level settings in your processor that can help Monero mining run faster. Mining usually continues, but you may get less speed than your processor could otherwise deliver. The warning is about a performance adjustment—not your wallet, pool connection, or missing mining rewards.

What XMRig is trying to change

MSR means model-specific register. These are controls inside your processor that operating systems and privileged software can access.

Monero uses RandomX, a mining algorithm—a set of calculations miners perform—that favors CPUs, your computer’s main processors. XMRig can adjust supported MSRs to make those calculations more efficient.

A common adjustment affects hardware prefetchers. These try to predict which data your processor will need next and fetch it early. That helps many everyday programs, but some prefetching behavior can hurt RandomX performance.

XMRig’s MSR changes depend on your processor model. They are not a universal speed boost for every CPU.

Why the adjustment fails

The warning means XMRig tried to make the change but could not complete it. Common causes include:

• Insufficient permissions. A normal user account usually cannot write to processor registers.
• Blocked access on Windows. XMRig needs a low-level driver for MSR access. Windows security features or a driver blocklist may stop that driver from loading.
• Unavailable access on Linux. The msr kernel module—the operating-system component that exposes these registers—may not be loaded, or system security rules may block writes.
• A virtual machine or container. Your mining environment may not expose the host processor’s registers, even if you have administrator access inside it.
• Unsupported hardware. Your processor may not support the particular adjustment XMRig attempts.

The log lines immediately before the warning often give you a better clue, such as a driver-loading failure or an access-denied message.

What you can safely check

First, make sure you are using a current, genuine XMRig release. Modified mining downloads can contain malware, and giving an untrusted program administrator access makes that risk much worse.

On a computer you own and control:

• Windows: Running a trusted XMRig copy as administrator may solve a permissions problem. If the log reports a blocked driver, check your Windows security notifications. Do not blindly disable antivirus, Memory Integrity, or driver protections just to remove the warning.
• Linux: Check whether the msr module is available and loaded. An administrator can usually load it with sudo modprobe msr, but XMRig still needs permission to access the registers.
• Virtual machines: Ask whether the platform supports MSR access. Extra permissions inside the guest may not help.

Avoid copying random register values from forum posts. Settings appropriate for one processor may be wrong for yours.

How much speed are you losing?

There is no reliable percentage that applies to everyone. The effect depends on your CPU, memory setup, and other mining settings.

Hashrate means how many mining calculations your computer performs each second. Compare XMRig’s settled hashrate before and after a successful adjustment under similar conditions.

This warning is separate from huge pages, a memory-management feature that also affects RandomX performance. Fixing one does not automatically fix the other.

The bottom line

You can usually keep mining with this warning. Check permissions and the surrounding log messages first, but accept slightly lower performance rather than weaken your computer’s security just to clear it.