cpupower: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/cpupower - from package: cpupowerutils

You may install the required package with command yum install {package}

Error in other languages:
cpupower: bevel nie gevind nie
cpupower: comandă negăsită
cpupower: comando não encontrado
cpupower: commande introuvable
cpupower: command not found
cpupower: käsku ei ole
cpupower: không tìm thấy lệnh
cpupower: komanda nerasta
cpupower: Kommando nicht gefunden.
cpupower: kommandot finns inte
cpupower: komut yok
cpupower: nie znaleziono polecenia
cpupower: níor aimsíodh an t-ordú
cpupower: no se encontró la orden
cpupower: no s'ha trobat l'ordre
cpupower: opdracht niet gevonden
cpupower: parancs nem található
cpupower: perintah tidak ditemukan
cpupower: príkaz nenájdený
cpupower: příkaz nenalezen
cpupower: команда не найдена
cpupower: командата не е открита
cpupower: 命令找不到
cpupower: コマンドが見つかりません