PCI-Express 4.0 Pushes 16 GT/s per Lane, 300W Slot Power

[btarunr]

The PCI-Express gen 4.0 specification promises to deliver a huge leap in host bus bandwidth and power-delivery for add-on cards. According to its latest draft, the specification prescribes a bandwidth of 16 GT/s per lane, double that of the 8 GT/s of the current PCI-Express gen 3.0 specification. The 16 GT/s per lane bandwidth translates into 1.97 GB/s for x1 devices, 7.87 GB/s for x4, 15.75 GB/s for x8, and 31.5 GB/s for x16 devices.

More importantly, it prescribes a quadrupling of power-delivery from the slot. A PCIe gen 4.0 slot should be able to deliver 300W of power (against 75W from PCIe gen 3.0 slots). This should eventually eliminate the need for additional power connectors on graphics cards with power-draw under 300W, however, the change could be gradual, as graphics card designers could want to retain backwards-compatibility with older PCIe slots, and retain additional power connectors. The PCI-SIG, the special interest group behind PCIe, said that it would finalize the gen 4.0 specification by the end of 2016.



View at TechPowerUp Main Site

 

[Nokiron]

Finally some interesting progress with PCI-E. I'm not so sure what would change with this though.

Where do you draw the limit where the motherboard might be the bottleneck with GPUs powered by the slot?

 

[Mussels]

300W slot power will be interesting, it'll make cards incompatible with old slots - and really heavy power draw from mobos.

I guess they'll need some kind of physical key system to prevent those cards going into older slots.

 

[btarunr]

Finally some interesting progress with PCI-E. I'm not so sure what would change with this though.

Where do you draw the limit where the motherboard might be the bottleneck with GPUs powered by the slot?

300W. The boards should have safety trips beyond that point, because you're delivering that power through traces, and not thick metal plugs. I imagine PCIe 4.0 motherboards with have PCIe power input connectors on the board.

 

[Frick]

I imagine PCIe 4.0 motherboards with have PCIe power input connectors on the board.

Aye, which makes it kinda moot IMO. The only benefit this has is cable management. And you break back backwards compatibility and looking at how little improvement there is in CPU performance it makes it downright bad.

Unless they make traces that really can do 300W, which is a lot.

 

[Caring1]

300W. The boards should have safety trips beyond that point, because you're delivering that power through traces, and not thick metal plugs. I imagine PCIe 4.0 motherboards with have PCIe power input connectors on the board.

I agree, they have already been doing similar with some boards by the addition of a Molex for extra power if needed.

 

[bonehead123]

4x the power flowing through the slots, and you will also have 4x the heat produced too

So it looks like the mobo makers are really gonna have to step up their game in terms of trace and slot design, to accommodate this change, cause if they dont, there's gonna be hell to pay from mutli-mega billion $$ lawsuits over melted mobos and anything and everything attached to them, not to mention desks and houses burned down etc...........

 

[Nokiron]

300W. The boards should have safety trips beyond that point, because you're delivering that power through traces, and not thick metal plugs. I imagine PCIe 4.0 motherboards with have PCIe power input connectors on the board.

Yeah, but that adds costs one way or another. This will inherently be more expensive than current solutions.

 

[JalleR]

Maybe Motherboards will have Physical cables on the back with this new standard

Quad SLI/CF support.....

And that will mean a new PSU standard as well i guess...

 

[AlienIsGOD]

I agree, they have already been doing similar with some boards by the addition of a Molex for extra power if needed.

My z77 ftw EVGA board has 4 pin molex on the board for that very reason

 

[Vayra86]

I wonder why we would need this.

 

[Nokiron]

My z77 ftw EVGA board has 4 pin molex on the board for that very reason

Yeah sure, but what with the budget-boards that suddenly need to be capable of 300W through the traces?

 

[lanlagger]

"slot should be able to deliver 300W of power".. AMD right now:

 

[RejZoR]

Ok, if 75W PCIe power delivery is such huge problem where people go batshit insane over RX480 issues, how are they planning to deliver PCB power traces to the PCIe slot without spontaneously combusting the board at 300W? Are they going to run external wires on the back of the boards? You can't make PCB traces that thick (well, you could, but it would be highly impractical), so, how?

 

[TheLostSwede]

You missed the most interesting part...

http://www.tomshardware.com/news/pcie-4.0-power-speed-express,32525.html

 

[Mussels]

ok external PCI-E cables that deliver 300W to an external box, THAT makes sense.

bring on the external GPU's that dont need their own PSU!

 

[TheLostSwede]

300W slot power will be interesting, it'll make cards incompatible with old slots - and really heavy power draw from mobos.

I guess they'll need some kind of physical key system to prevent those cards going into older slots.

Why would it make older card incompatible? The Voltage won't change, so there's nothing here to make older stuff incompatible, it's an increase in Amperage. A card will never draw more power than it was designed for, so this is a non-issue.

Time to learn some basics before making statements like that me thinks...

 

[TheLostSwede]

Ok, if 75W PCIe power delivery is such huge problem where people go batshit insane over RX480 issues, how are they planning to deliver PCB power traces to the PCIe slot without spontaneously combusting the board at 300W? Are they going to run external wires on the back of the boards? You can't make PCB traces that thick (well, you could, but it would be highly impractical), so, how?

The same way some companies have been for years, 12V cables to somewhere close to the connectors on the motherboards. In other words, this won't help with the cable clutter...

 

[Mussels]

Why would it make older card incompatible? The Voltage won't change, so there's nothing here to make older stuff incompatible, it's an increase in Amperage. A card will never draw more power than it was designed for, so this is a non-issue.

Time to learn some basics before making statements like that me thinks...

not sure if i worded it badly, i meant new cards incompatible with older boards.

 

[Frick]

Why would it make older card incompatible? The Voltage won't change, so there's nothing here to make older stuff incompatible, it's an increase in Amperage. A card will never draw more power than it was designed for, so this is a non-issue.

Time to learn some basics before making statements like that me thinks...

It makes new cards incompatible with old boards.

 

[Caring1]

not sure if i worded it badly, i meant new cards incompatible with older boards.

I understood that when I read it, but if the cards still have the 6 and 8 pin sockets they will be compatible.

 

[Mussels]

I understood that when I read it, but if the cards still have the 6 and 8 pin sockets they will be compatible.

not if they do an RX480 and balance the draw incorrectly...

 

[Prima.Vera]

300W slot power will be interesting, it'll make cards incompatible with old slots - and really heavy power draw from mobos.

I guess they'll need some kind of physical key system to prevent those cards going into older slots.

Shouldn't be the case since the Voltage will be the same. Is just the the slot would be able to deliver a lot more power now if required.
The question is, are the mobo manufactures still going to use the cheap shitty plastic to build the PCI-Express slots, or they will going to use other material, much more heat resistant?

Price increase seems like a no brainer....

 

[Keullo-e]

My z77 ftw EVGA board has 4 pin molex on the board for that very reason

I had a S939 board with a molex connector 10 years ago, so that truly isn't a new invention. I guess it was like for 7600GT SLI or something similar; cards which doesn't have a power connector, but two of them could be too much for a motherboard.

 

[matar]

300w Slot power sweet no 6 pin or 8 pin power connecters = nice looking case no sticking out cables.