Should I refresh my servers or just upgrade my CPUs ?

There has been lots of discussion recently about whether its better to replace or upgrade existing CPUs in your installed base of servers rather than purchase new servers. I wanted to share some thoughts with you that might clarify why a new server purchase is the better option for most IT departments.

Here are some of the challenges that an IT department must face when considering replacing CPUs rather than buying new servers.

  1. Does the existing system support the new CPU – most CPUs require specific BIOS versions, is there a BIOS update available for the server that supports the new CPU ? Also the server motherboard may not have been tested by the OEM with the new CPU.
  2. Has the software stack you are running on the server  been validated on the new CPU.
  3. Replacing a CPU is a non-trivial exercise – it takes time and you run the risk of damaging a working server
    • the server must be shut down and dismantled to access the existing CPU
    • the existing CPU/heatsink combo must be removed. The heatsinks used by OEMs in branded servers are specifically designed for the server in which they are used. These heatsinks typically have significant mass so they are usually very firmly attached to the server chassis to prevent damage due to shock and vibration whilst in transit and in use.
      • The existing heatsink must be removed from the current CPU, which may not be easy if the system has been in use for some time the thermal bonding may have hardened permanently attaching the heatsink to the CPU.
      • The heatsink must be attached to the new CPU – with the appropriate thermal bonding.
      • The CPU/heatsink combo must then be correctly re-installed in the system and the system re-assembled.
    • It is also necessary to take into account that removing/changing a CPU may also void or otherwise affect the system warranty.

    It is conceivable that some IT folk may want to consider this approach but the risks associated with undertaking this operation are very high and many IT departments will take the approach of not touching working systems.  If you are still not convinced its also worth considering -

    • Replacing the CPU in an old server may not significantly improve its energy efficiency. The latest generation server designs not only use latest CPUs but they incorporate many new features that improve the overall energy efficiency of the complete platform – making them a much better proposition when looking to reduce overall data centre utility bills and OpEx costs.
    • Upgrading the CPUs in an old server may expose other limitations of the server in terms of memory and I/O, this could result in having to upgrade many other parts of the server resulting in an overall higher cost than replacing the server with a new purpose designed solution

    So, as far as I can see very few IT departments are going to seriously consider replacing CPUs in their existing installed base and will look instead to deploy latest generation high performance energy efficient server designs – i.e. servers based on Xeon 5500 or Xeon 7400

    What’s your opinion – are you prepared to attempt to upgrade your CPUs or will you refresh the complete server system to get the latest technology for all elements of the server platform