I realize that PCs are quirky beasts; but they are quirky beasts architecturally very similar to(typically more powerful than, for any vaguely serious gaming system) both contemporary consoles
How does this happen?
You are thinking like a PC gamer and thinking about ONLY the CPU and GPU when you compare the PC to the current gen consoles. Machines aren't just CPU's and GPU's, they have internal busses, I/O, RAM. Those matter.
And when it comes to those things, consoles are still specialized beasts.
Lets take the PS2. There were PC gamers claiming their GeForce 3 was better, their CPU faster, etc etc. That may have been true, but the PS2 wasn't an ordinary PC, it had specialized RAM and specialized internal busses. It could do things that a PC of that era simply could not do.
http://archive.arstechnica.com...
http://archive.arstechnica.com...
Watch the vector unit demos. They're running entirely on the vector unit in 16K of RAM, no CPU involved.
https://www.youtube.com/watch?...
IIRC, somebody came up with a Zlib implementation that ran entirely on a PS2 vector unit.
The PS3 is similar, fast Rambus RAM, SPU's, and fast internal busses. IIRC somebody smarter than me referred to it as "taking the multiprocessin ideas introduced with the PS2, further"
The PS4 is more "normal", but still has specialized RAM and internal busses. You simply can't buy a PC with GDDR5 main ram. Imagine if you had a PC with ALL of it's RAM as fast as the RAM on the video card. That would be nice, wouldn't it? But that can't happen, the PC is limited by PCIe.
The PS4 isn't.
http://www.gamasutra.com/view/...
It can move data around in ways a PC simply can not do. It also doesn't have to deal with the problem that is Windows. Windows is a general purpose OS, even when it runs games.
The PS4 runs BSD, while it is also a general purpose OS, there's no need on the PS4 to keep "desktop computer services" running. The PS4 doesn't have to keep a print spool up, have a java updater constantly running, . It doesn't have to worry about the "needs" of an Office suite, or SMB shares, or Norton/Kaspersky/AVG, or any of the other things a PC does. It runs games. It can do other things as well but it's design focus is on games more than anything else.