In the same way as we can add graphics cards to a PC using the PCIe expansion slots, what prevents us from being able to add more additional processors to a PC in this same format? Is it possible to create an x86 CPU in PCIe card format ? In this article we are going to tell you why nowadays something like this is neither done nor can be done.
It would be ideal, right? Imagine that you have a PC in which the processor has become obsolete and becomes a bottleneck, so you simply buy a new processor in PCIe expansion card format, connect it to your PC and you already have all its power added to the processor you already have. you had. It is a sadly utopian scenario that, in today’s consumer electronics, it is not possible to create, and then we will tell you why.
A CPU in PCIe format, the dream of modular hardware
Much has been said and speculated on modular hardware, whereby with removable expansion cards we can add and remove hardware components on the PC. Already in ancient times we saw, with the Pentium II, that the processor was connected to the motherboard in a format similar to this, in fact.
This would be the dream of modular hardware, since when the processor falls short or we simply want to change it for a better one, it would be in a “detachable” format, with the addition of the universality of the PCI-Express socket that would allow us to do so without having to change the motherboard and without depending on the socket. In fact, in this way we could add as many processors as there are PCIe sockets on the motherboard, gradually adding raw power to the system.
However, the current hardware architecture prevents us from making this dream a reality, at least in the way that we have described because, in reality, this technology does exist but conceived in a different way.
Accelerator cards and coprocessors
In a PC, we always say that the brain that manages everything is the processor, and in reality this is practically how the computer architecture that we use in this era works: absolutely everything goes through the processor. However, it is possible to add computing power through PCIe expansion cards, and in fact this is how the graphics cards that we all use on a daily basis work.
In addition to that, although we cannot find them in the consumer market but are more oriented to the business market, there are accelerator cards and coprocessors, whose function is not exactly to add an x86 processor as such to the system to add to the one we already have installed in the motherboard socket, but they have specific functions that literally serve to speed up certain operations and relieve the processor of load, precisely.
There are, in fact, complete servers in PCI-Express expansion card format, but their use is so highly specific and limited that their cost becomes quite difficult to supply even for the business environment. In any case, they are still programmable accelerator cards with specific functions, they are not a processor that you add to the system and add its power to the one you already have.
Why is this technology not developed?
Seeing this we cannot help but wonder what manufacturers are waiting for to bring this PCIe CPU technology to consumer computing, and the answers to this are various. To begin with, in consumer computing we have processors powerful enough not to need a second CPU operating in tandem, and in environments where it is needed, there are already motherboards with two or many more sockets that allow several processors to be installed simultaneously, for so it doesn’t make much sense to focus R&D efforts to develop this kind of modular hardware when you already have alternative solutions that work well.
On the other hand, there are also certain limitations to do this, such as the bandwidth of the PCIe lanes, which, after all, always depend on the main processor. In other words, no matter how much you have a board with several processor sockets, there will always be a “master” and the rest will be “slaves” dependent on the first, just as ATA hard drives worked in ancient times.
As if this were not enough, we must remember that each of the processors needs its own RAM to function, so the development of a CPU in PCIe would no longer be a matter only of the processor itself, but would have to carry its own RAM, its chipset and everything else. It is something that, at present, although it would be conceptually viable, is not economically or practically viable.
