HP Server Processors

Xeon and Opteron CPUs for ProLiant servers, ordered by HP spare part number

About Server Processors

HP and HPE server processors are ordered by spare part number, not by the Intel or AMD model alone. The same Xeon SKU can appear under several HP part numbers depending on which ProLiant generation it was qualified for and how it was supplied.

B21 and L21 suffixes are not interchangeable

Two suffixes dominate HP processor part numbers, and they mean different things:

  • -B21 is an option kit, sold for field upgrade. It normally includes the heatsink needed to populate a second socket.
  • -L21 is a factory-integration kit, supplied when the CPU was installed on the production line.

Both contain the same silicon. What differs is what ships alongside it, which matters when you are adding a second processor to a machine that was built with one.

What is in stock

  • Intel Xeon across the E5-2600, E5-4600 and E7 families, plus earlier 5000 and 5100 series parts
  • AMD Opteron for the ProLiant lines that shipped with it
  • Sockets from LGA771 through FCLGA2011-3, spanning ProLiant G5 to Gen10
  • Core counts from single-core legacy parts up to 22-core E5-4600 v4

Three things that decide whether a CPU will work

Socket match is necessary but not sufficient. A processor also has to be supported by the system ROM in that specific ProLiant generation, and in a dual-socket board both processors must be the same model. Adding a second CPU usually requires the matching heatsink, and in many chassis an additional fan.

Memory population rules change with the processor too, because each CPU owns its own memory channels. See HP server memory for the DIMM side of the same upgrade.

Send us the ProLiant model and generation and we will confirm the processor, heatsink and fan together rather than guessing from the socket alone.

Featured Server Processors Products

Browse all 36,513 Server Processors SKUs.

Frequently Asked Questions

What is the difference between an HP -B21 and -L21 processor kit?

Both contain the same processor. A -B21 is an option kit sold for field upgrades and normally includes the heatsink required to populate a second socket. A -L21 is a factory-integration kit, supplied when the CPU was fitted during manufacture. If you are adding a second processor to an existing server, the -B21 kit is usually what you want because of the heatsink.

Can I mix two different Xeon models in one ProLiant?

No. In a dual-socket ProLiant both processors must be the same model, stepping tolerances aside. Mixing speeds, cache sizes or core counts is not supported and the server will typically refuse to boot or will run only the first processor.

Does a matching socket mean the processor will work?

Not on its own. The processor also has to be supported by the system ROM of that particular ProLiant generation. Several sockets, notably LGA2011 and FCLGA2011-3, carried more than one processor generation, and a board will only run the families it was qualified for. Send us the server model and we will confirm.

Do I need anything besides the processor to add a second CPU?

Usually yes. A second socket needs its own heatsink, and many ProLiant chassis also require an additional fan module to be fitted before the second processor is recognised. Option kits with the -B21 suffix generally include the heatsink; the fan is often a separate part.

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