Motherboard PCIe 4.0 in 2017?

[BirdofPrey]

The major problem is not the inter symbol interference between adjacent differential pairs. Electricity behaves differently when the frequency increases. 16 Ghz direct base band signalling creates a spectrum that carries information up to 32 Ghz in harmonics. Frequencies beyond this are less important to signal reconstruction at the receiver. At these multi Ghz frequencies, a shielded twisted pair is a poor transmission line because it acts as a low pass filter with decreasing gain frequency characteristics and non-linear phase delay. It also produces too much skin effect, radiates power (n λ/ 4 antenna segments), and discontinuities like bending causes signal reflection and standing waves. Electricity prefers to travel as electromagnetic waves at these frequencies. This is the area of wave guides. On PCBs, wave guides take the form of micro-strip lines. Metallic wave guides, although suited for communication and radar, can not be easily manufactured into flexible cables used for connecting peripherals to PCs. Die electric wave guides are flexible, but they become practical only at multi-THz range. Die electric wave guides, made with a core, cladding and protective jacket, carrying 100s of Thz signal (light) modulated with information are called optical fibers. This is the logical evolution of twisted pairs and coaxial cables to optical fibers when the signalling rate increases beyond 10s of Ghz.

(Sorry for all the bad grammar and spelling )

Ah, alrighty then. Did not know that.
I'm confused about your comments on waveguides not being useful below THz ranges though, since I was under the impression coaxial cables were waveguides for radio and microwave frequencies.

 

[Phuncz]

It will indeed take time but could also lay the groundwork for the 12V-only PSUs, maybe even with just one cable (or card-edge) if storage could also piggy-back from the motherboard. I don't see why not, considering U.2 connectors.

This could lead to very efficient PSUs, but also much more expensive motherboards due to offloading much of the PSU's roles towards the motherboard.

 

[hardcore_gamer]

I'm confused about your comments on waveguides not being useful below THz ranges though, since I was under the impression coaxial cables were waveguides for radio and microwave frequencies.

Die-electric (non-conducting) wave guides like optical fibers aren't useful below infra red frequencies. This is because die-electrics like silica glass can reflect and guide light but can't efficiently reflect radio/microwaves.

Metallic wave-guides can guide microwaves , but they aren't flexible. They're also difficult to manufacture with good tolerances as the operating frequency increases. Coaxial and shielded twisted pairs operate at even lower frequencies.

 

[jeshikat]

Well that's disappointing. Tom's Hardware updated their article and it turns out that the slot will still be 75W after all: http://www.tomshardware.com/news/pcie-4.0-power-speed-express,32525.html

 

[hardcore_gamer]

Well that's disappointing. Tom's Hardware updated their article and it turns out that the slot will still be 75W after all: http://www.tomshardware.com/news/pcie-4.0-power-speed-express,32525.html

Makes sense. Why waste precious PCB area with thick traces and additional circuitry when simple 18-gauge wires can do the job?

 

[Phuncz]

Because those wires also need connectors and a path to the PSU. Eliminating both would be very beneficial not only for SFF, but everyone else with a >75W TDP GPU.

GPU manufacturers are wasting PCB area anyways with insanely overspecced power circuitry that rarely can show its potential due to these being meant for insane overclocks.

 

[CC Ricers]

Makes sense. Why waste precious PCB area with thick traces and additional circuitry when simple 18-gauge wires can do the job?

Kind of disappointing that it's still 75W but I also agree on points like this one. Designing the boards to be able to deliver 40A and add the proper power management circuitry to every PCIe 4.0 slot would drive prices up. At least I would've liked an increase to 100 or 120W though...

 

[BirdofPrey]

GPU manufacturers are wasting PCB area anyways with insanely overspecced power circuitry that rarely can show its potential due to these being meant for insane overclocks.

As neat as overclocking can be, I admit, I do get tired of every single time a product comes out it get pounced on over how good it overclocks, and is always deemed unworthy if it can't overclock more than the last product.

Kind of disappointing that it's still 75W but I also agree on points like this one. Designing the boards to be able to deliver 40A and add the proper power management circuitry to every PCIe 4.0 slot would drive prices up. At least I would've liked an increase to 100 or 120W though...

Yeah higher wattages from the slot would have been nice, but 300W did seem kind of dubious even for a 1 slot system. mATX would be looking at 600W and ATX would be looking at 900-1200W.
I just can't see that being feasible and affordable at the same time.