There are many users who dream of fully modular PCs, where no component is linked to another beyond its own platform. This is something more or less achievable with graphics cards, where we can connect any device with certain devices to a laptop and enjoy an increase in power. But why is this not possible with processors? Will the concept of external CPU exist in the future?
It is not an easy topic to deal with on the one hand, but on the other there are high hopes for it, so let’s go piece by piece on this path that will surely be long. Why don’t AMD and Intel currently work on external CPUs, especially focused on low-power equipment that may need extra power at any given time?
External CPU, from the impossible to the possible
Having an external processor that can be connected to any PC to give it more performance is an idea that has been on the table for many years and is partly a reality. Intel with its Xeon Phi took the step in 2010 with this idea and surprisingly, this 2020 has canceled its Knights Hill architecture at 10 nm.
The idea is basically what we are dealing with in this article: a CPU that can be connected to a PC externally, except that Xeon Phi did it in a somewhat particular and well-known way: through PCIe.
Basically it was a GPGPU focused as a CPU with MIC architecture to create a multiprocessor that could work with the tools of the existing parallelization software for deep learning. But then, why was it canceled if it worked as such? Taking into account that the sector that Xeon Phi was focused on was business and data centers, it should be borne in mind that GPUs do a normally better and faster job, where in addition Intel will have its new Xe graphics cards. for that end.
Therefore, Xeon Phi was meaningless as such and had to be left to die. But Intel proved that it is viable, so why not use it on desktop?
Speed and cost issues
There are two problems for which this technology is not going to be carried out for the desktop in a short period of time at least: the connection speed between devices and of course the cost of such a system.
Starting with the connections, the fastest that currently exists under PCIe is Thunderbolt 4 and even so with its 40 Gbps it is a ridiculous figure for the amount of data that a current CPU manages to move. Although we consider tasks very specific to it because of this, we must add the amount of latency that is generated between PCIe, connection, PCIe and the main CPU of the master device.
Only in certain situations this can be ignored and the result would be satisfactory, since like Xeon Phi, an exclusive and task-oriented programming is needed. As for the cost, the Intel architecture had integrated memory, the chip was installed in a giant interposer and in general, it was like using a PCB from a graphics card with a CPU with IHS in its nerve center.
If a CPU in itself is expensive, here we would surely be paying almost a complete system of processor, motherboard and memories, since it is more a SoC to use than a CPU as such. The costs, as demonstrated by Xeon Phi, are not acceptable for the normal user, and using more basic versions does not reduce that cost too much, since the CPU matrix could be very similar to the desktop one, but the other components would have to be specific.
Mobility
The main problem with this type of technology is that they are not designed for mobility, but for the opposite. They would be useful for the user who works with their laptop outside the home and when they arrive they only have to connect a cable to enjoy more power.
For the rest, it is nonsense to go from one side to the other with a laptop and a system that could be like a shoe box approximately. In fact, it is difficult for external GPUs to continue selling as such because their market is low, very low, and that is supported by industry giants such as ASUS, GIGABYTE or Razer with their respective devices with a power supply included.
But the reality is that as a general rule it is not practical, and if we add everything said to an external CPU, it is very possible that this idea is not developed for the desktop while everything remains the same. Another approach is the Intel Compute Elements approach , where CPU, RAM, and storage are all tied together on a PCB that is at the same time cooled and connected like a card via PCIe.
It is not a concept of pure CPU as such, but it is the latest that Intel has launched that resembles it and from what is being seen, it will remain in a much more closed market than that of the NUC themselves.