Windows Server OEM licensing is cheaper, but not always.
To be specific OEM licensing has many limitations:
- Licenses are non-transferable (to another computer)
- Licenses expires with the hardware
- A change of motherboard or processor will deem an OEM license invalid and a new license will have to be purchased as it is similar to changing to a new system
- There is No upgrade path
- You will need to keep the COA (certificate of authenticity) and invoice (OEM license is purchased with hardware) as proof of license
- No on-line tracking
- No re-imaging rights. You cannot create custom images and deploy using third Microsoft or third party tools
- If a license is lost, damaged in fire/flood or stolen, new licenses needs to be purchased as there is no way of replacing those licenses as Microsoft does not keep track of the licenses.
- Each install has different license key and will need to be activated online. You cannot use a Volume license key to install OEM licenses
- No multiple language rights
- Support is the responsibility of the OEM reseller (probably you), not Microsoft.
