intel_max_boost

Apply max-boost MSR tuning on Intel Xeon Gold (Skylake-SP).

WARNING: writing MSRs can crash, overheat, or permanently damage hardware. Requires an unlocked-MSR BIOS (pre-Plundervolt-mitigation). Use at your own risk. Tested on Dell 7820, Xeon gold 6138

What it does

intel_max_boost.sh:

1. Sets the CPU governor to performance (required so 0x199 / PERF_CTL sticks).
2. Writes 13 MSRs to all CPUs via wrmsr -a.
3. Verifies every MSR with rdmsr -p <cpu>. All are strict except 0x64F, whose upper 16 bits are HW-dynamic — only the lower c000 is checked.

Notes:

• 0x610 is package-scope; writing it once per CPU is harmless.
• Pairs well with the Intel Undervolt utility for core/cache/uncore undervolting.

Requirements

• Root (sudo)
• msr-tools (wrmsr, rdmsr)
• modprobe, lscpu (usually preinstalled), optional cpupower
• Unlocked MSR BIOS

Install on Debian/Ubuntu:

sudo apt install msr-tools linux-cpupower

Usage

sudo ./intel_max_boost.sh --help
sudo ./intel_max_boost.sh --dry-run        # print what would be done
sudo ./intel_max_boost.sh                  # real run, logs to /var/log/msr-apply.log
sudo ./intel_max_boost.sh --log-file ""    # log to stdout only

To re-apply at boot, add a systemd unit or cron @reboot entry calling the script with an absolute path (not shipped in this minimal release).

MSR values

MSR	Value	Verify
0x48	0x0	strict
0x4E	0x2	strict
0x199	0x2500	strict
0x1A0	0x850089	strict
0x1A4	0x2	strict
0x1B0	0x0	strict
0x1B2	0x0	strict
0x38D	0x330	strict
0x38F	0x70000000f	strict
0x3F1	0x0	strict
0x610	0x28b1800fe8b18	strict
0x64F	0xc000c000	lower16 c000 only
0x770	0x0	strict

License

MIT — see LICENSE.