最近看到許多 Zen, Zen+ 架構的 4C, 6C, 8C CPU 在二手市場，價格都很平易近人。但我下個新的 Home Lab Headles 伺服器，應該會朝 Zen2 或更新的架構選擇，主要原因在於 CPPC (Collaborative Processor Performance Control)。

Linux 核心有支援 CPPC，如果在 BIOS 有開啟該選項，系統會載入 amd-pstate-epp 取代 acpi-cpufreq，可以讓 Zen2 以上的 CPU 以較低的頻率執行，有助於將低功耗。

下面是我的 R3-3100 資料提供各位參考：

amigo@R3-3100:~$ cpupower frequency-info
analyzing CPU 6:
driver: amd-pstate-epp
CPUs which run at the same hardware frequency: 6
CPUs which need to have their frequency coordinated by software: 6
maximum transition latency: Cannot determine or is not supported.
hardware limits: 400 MHz - 4.11 GHz
available cpufreq governors: performance powersave
current policy: frequency should be within 400 MHz and 4.11 GHz.
The governor "powersave" may decide which speed to use
within this range.
current CPU frequency: Unable to call hardware
current CPU frequency: 3.50 GHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: yes
AMD PSTATE Highest Performance: 255. Maximum Frequency: 4.11 GHz.
AMD PSTATE Nominal Performance: 236. Nominal Frequency: 3.80 GHz.
AMD PSTATE Lowest Non-linear Performance: 148. Lowest Non-linear Frequency: 2.38 GHz.
AMD PSTATE Lowest Performance: 25. Lowest Frequency: 400 MHz.

amigo@R3-3100:~$ cpupower idle-info
CPUidle driver: acpi_idle
CPUidle governor: menu
analyzing CPU 1:

Number of idle states: 4
Available idle states: POLL C1 C2 C3
...skip...