CPUs don’t always have the same pinout as their corresponding sockets, and some manufacturers (Intel most notably) will not allow you to run a dual CPU motherboard with only one CPU installed.
Now let’s assume that for whatever reason I do want to install one Intel processor into an Intel dual CPU motherboard.
Dual CPU motherboard with only one CPU.
Absolutely – All server motherboards will support either a single or dual CPU.
There are a few things to note though if you intend to use a single CPU on a dual CPU-capable motherboard.
Most motherboards will split certain IO or functionality over both CPUs, for “load balancing” and to enable certain features. In the majority of boards this means;
- Only half of the PCIe slots will be active if a single CPU is installed.
- On modern boards, PCIe NVMe OcuLink ports tend to only be connected physically to the second CPU. This does vary by board design, but the majority of Asus and Supermicro motherboards are set up this way
- Onboard SAS – If your motherboard has an onboard SAS controller (such as an 8087 or 8643 port) then this usually connects via PCIe to a second CPU and wouldn’t function with a single CPU.
Whilst on the subject of dual CPU boards – I thought I’d detail our most popular dual CPU boards – They’re the best priced and have excellent availability.
I read the manual get my system running, and then install a second processor in order to dual boot two operating systems (such as Windows XP Pro/Ubuntu Linux) independently on each CPU.
Two Computers with One CPU
I put the processor(s) in place, but now what? Well, that all depends if I used pins 1-1 to 16-16, or 1-1 to 8-8.
Let me explain:
A dual CPU motherboard works in the same manner as a dual-core processor: two separate channels. The difference is that with the motherboard you have four pins instead of eight for each channel, and these pins are used for intercommunication between processors as well as power delivery. In the case of a dual-core processor, only two pins are really needed to carry information between processors, but four or more are needed to supply power.
The CPU is wired (pinned) in such a way that each set of pins can be used for intercommunication with another socket on the motherboard.