Isso funcionou para mim em um OEM Dell Laptop. Se bem me lembro, usei uma instalação genérica do Windows 7 que era do mesmo tipo (pro) e quando não tinha uma chave para ativação (porque o windows é ativado via hardware), isso funcionou. Sua "milhagem" varia.
In windows Vista, 7, server 2008, 2008r2, and server 2012 OEM activation is accomplished by the combination of 3 elements.
The bios of the system must contain what is called a “SLIC” string, all systems made by a major OEM such as Dell, HP will include this. Home built systems will not (unless you modify the bios yourself) A certificate file that matches up against the “SLIC” string that is stored in the BIOS. These certificate files are unique to each OEM so Dell has their own, HP has their own, etc. and are not interchangeable. A Windows product key that tells the system to use OEM activation instead of the traditional Microsoft activation process. These keys are not specific to a particular OEM and are interchangeable. If all 3 are present the system is instantly activated, does not communicate with MS to determine if activation is valid or to activate against a MS server. The activation is already trusted.
When you rebuild a PC component 1 is still present but #2 and # 3 are missing.
Attached in the SLIC.zip file you will find the certificate files used by Major OEM’s such as Dell, HP, Lenovo, as well as product keys that can be used for Windows 7 Professional, and Ultimate.
Download do arquivo ZIP do SLIC
To use this, for example if you had a Dell.
Open an elevated command prompt, extract the Dell certificate to C:\temp
The certificate is called Dell-Dell-2.0.xrm-ms
So issue the command slmgr –ilc c:\temp\dell-dell-2.0.xrm-ms
Then issue the command slmgr –ipk 2QTV2-3CMPP-FQBYK-XXXXX-XXXXX (For windows 7 Pro)
Wait about 5 seconds and if you look that system is now genuine and activated.