How PCIE Lanes work?

[TechyInAZ]

I already know what PCIE lanes are and what they do, but i'm not that familiar with how the CPU and chipsets PCIE lanes work together.

How many PCIE lanes come with a Z97 chipset?

How do you know what PCIE slots go to either CPU or chipset?

Thank you,

 

[jdcranke07]

I already know what PCIE lanes are and what they do, but i'm not that familiar with how the CPU and chipsets PCIE lanes work together.

How many PCIE lanes come with a Z97 chipset?

How do you know what PCIE slots go to either CPU or chipset?

Thank you,

As far as I'm aware, granted I'm not an expert on this yet, I'm pretty sure the CPU determines how many PCI-E lanes are available to you. And a Z97 mobo tops out at 24 lanes and a X99 can have up to 40 depending on the CPU. I also believe that all lanes go through in some way the chipset and the CPU. I could be wrong though.

 

[Dark Lord of Tech]

One of my bookmarks.
http://www.hardwaresecrets.com/printpage/everything-you-need-to-know-about-the-pci-express/190
A lot of info.

 

[jdcranke07]

One of my bookmarks.
http://www.hardwaresecrets.com/printpage/everything-you-need-to-know-about-the-pci-express/190
A lot of info.

Learning has occurred, thanks.

 

[cub_fanatic]

The PCIe controller is not on the motherboard, it is on the CPU itself when talking about late model Intel chipsets and CPUs like the Z97 and Haswell for example. Natively, as in what the CPU comes with, mainstream 1150 CPUs typically have 16 PCIe 3.0 lanes. If the motherboard has its own PCIe controller which some enthusiast level boards do, this number could go up to 32. This is usually accomplished with a "PLX" chip.

 

[Eximo]

Well, it is more or less dependent on the CPU entirely these days. So your CPU really sets your PCIe bandwidth and lanes. For LGA1150 Haswell chips that is 16 PCIe 3.0 Lanes.

Chipset acts as the controller of the lanes and in the case of Z97 adds another 8x PCIe 2.0 lanes. So depending on what you plug in it will automagically assign lanes in the most proper manner to achieve the best possible configuration. Also has your native intel USB, SATA, and all that stuff there.

 

[TechyInAZ]

The PCIe controller is not on the motherboard, it is on the CPU itself when talking about late model Intel chipsets and CPUs like the Z97 and Haswell for example. Natively, as in what the CPU comes with, mainstream 1150 CPUs typically have 16 PCIe 3.0 lanes. If the motherboard has its own PCIe controller which some enthusiast level boards do, this number could go up to 32. This is usually accomplished with a "PLX" chip.

I'm familiar with PLX chips, but i thought all H and Z chipsets came with some pcie lanes built in?

 

[TechyInAZ]

Well, it is more or less dependent on the CPU entirely these days. So your CPU really sets your PCIe bandwidth and lanes. For LGA1150 Haswell chips that is 16 PCIe 3.0 Lanes.

Chipset acts as the controller of the lanes and in the case of Z97 adds another 8x PCIe 2.0 lanes. So depending on what you plug in it will automagically assign lanes in the most proper manner to achieve the best possible configuration. Also has your native intel USB, SATA, and all that stuff there.

Ok this makes sense.

So to give an example:

Say I have this configuration on my Asus Z97-A:

PCI x1 = Asus USB 3.1 Card
PCIE 3.0 x16 (x8 mode)= GTX 960 SLI
PCIE 3.0 x16 (x8 mode)= GTX 960 SLI
PCIE 2.0 x16 = Asus Thunderbolt Card

First off, would this configuration even be possible lol?

Would the 960s in SLI use only all the CPU lanes?
Would the add on cards use the Chipset lanes?

BTW...This is just an example, I have no plan on actually doing a setup like this.

 

[cub_fanatic]

The PCIe controller is not on the motherboard, it is on the CPU itself when talking about late model Intel chipsets and CPUs like the Z97 and Haswell for example. Natively, as in what the CPU comes with, mainstream 1150 CPUs typically have 16 PCIe 3.0 lanes. If the motherboard has its own PCIe controller which some enthusiast level boards do, this number could go up to 32. This is usually accomplished with a "PLX" chip.

I'm familiar with PLX chips, but i thought all H and Z chipsets came with some pcie lanes built in?

Yes, they have 8 PCIe 2.0 lanes on the motherboard which are used for the M.2 slot, non-GPU expansion cards (if the board even comes with PCIe 2.0 slots) as well as the rarely found on PC Thunderbolt interface. http://www.pugetsystems.com/labs/articles/What-is-new-in-Z97-and-H97-561/

 

[TechyInAZ]

The PCIe controller is not on the motherboard, it is on the CPU itself when talking about late model Intel chipsets and CPUs like the Z97 and Haswell for example. Natively, as in what the CPU comes with, mainstream 1150 CPUs typically have 16 PCIe 3.0 lanes. If the motherboard has its own PCIe controller which some enthusiast level boards do, this number could go up to 32. This is usually accomplished with a "PLX" chip.

I'm familiar with PLX chips, but i thought all H and Z chipsets came with some pcie lanes built in?

Yes, they have 8 PCIe 2.0 lanes on the motherboard which are used for the M.2 slot, non-GPU expansion cards (if the board even comes with PCIe 2.0 slots) as well as the rarely found on PC Thunderbolt interface. http://www.pugetsystems.com/labs/articles/What-is-new-in-Z97-and-H97-561/

Thank you, you solved my question!

One more thing (kinda off topic), since thunderbolt uses the pcie lanes on the chipset, will USB 3.1 use the pcie lanes on the chipset too? (For example the Asus Z97-PRO/USB3.1.)

 

[cub_fanatic]

The PCIe controller is not on the motherboard, it is on the CPU itself when talking about late model Intel chipsets and CPUs like the Z97 and Haswell for example. Natively, as in what the CPU comes with, mainstream 1150 CPUs typically have 16 PCIe 3.0 lanes. If the motherboard has its own PCIe controller which some enthusiast level boards do, this number could go up to 32. This is usually accomplished with a "PLX" chip.

I'm familiar with PLX chips, but i thought all H and Z chipsets came with some pcie lanes built in?

Yes, they have 8 PCIe 2.0 lanes on the motherboard which are used for the M.2 slot, non-GPU expansion cards (if the board even comes with PCIe 2.0 slots) as well as the rarely found on PC Thunderbolt interface. http://www.pugetsystems.com/labs/articles/What-is-new-in-Z97-and-H97-561/

Thank you, you solved my question!

One more thing (kinda off topic), since thunderbolt uses the pcie lanes on the chipset, will USB 3.1 use the pcie lanes on the chipset too? (For example the Asus Z97-PRO/USB3.1.)

USB 3.1 will be using its own controller and will be backwards compatible with USB 3.0 and 2.0. On modern systems that have USB 3.0, like the Z97, this controller is known as the Extensible Host Controller Interface or xHCI . USB 2.0 and 3.0 use xHCI version 1.0 and systems that are going to include USB 3.1 will use xHCI version 1.1. Like PCIe, there is the native Intel xHCI controller which only supports a limited number of USB ports. If the motherboard vendor wants to include more USB 3.0 ports, they can add another xHCI controller chip to the board similar to the PLX. This is why you have to sometimes install two different drivers for USB 3.0.

Besides increased bandwidth, one of the major changes will be increased wattage and voltage when the interface is used for charging. I read that it will be able to deliver up to 100 watts and 20 volts which is higher than even a PCIe 3.0 x16 slot which is only capable of 75 watts and 12 volts. Thanks to this increased wattage, large devices like a laptop can be charged with only the USB cable and a wall charger replacing the typical power bricks found on current laptops.

The only way that USB would affect the PCIe lanes is if you are using a USB expansion card.

 

[TechyInAZ]

Oh nice!! So that's why the new macbook can charge itself with a usb C cable.

Thx for the information.

 

[jdcranke07]

Oh nice!! So that's why the new macbook can charge itself with a usb C cable.

Thx for the information.

The new macbook has a draw back. You can only use the one port they have for charging the laptop or for data transfer or for visuals. It can only handle one task at a time not all of them at once. Not to mention everything is passively cooled since there is no fan anymore.

 

[cub_fanatic]

Oh nice!! So that's why the new macbook can charge itself with a usb C cable.

Thx for the information.

The new macbook has a draw back. You can only use the one port they have for charging the laptop or for data transfer or for visuals. It can only handle one task at a time not all of them at once. Not to mention everything is passively cooled since there is no fan anymore.

I hope this is not the case. According to this article, you should be able to charge and transfer data over the same USB 3.1 cable at the same time (link):

In real world use this will mean much faster charging of compatible mobiles, tablets and now even laptops. This can be done while transferring data at the same time, something previous standards could not always manage.

This should also mean the need for a separate power port, with large innards, will be gone allowing manufacturers to make even smaller laptops for example.

But, even if this doesn't work the way they say it will, thanks to these crazy low 5 watt TDP Core-M CPUs, it probably won't be much of an issue anyway since batteries are going to last much longer. This is also why there are no fans, these CPUs significantly less heat than many tablets and cell phones which has a lot to do with clock speed throttling as well as the 14nm process Intel is now using to make these chips. The 20nm A8 SoC found in the iPhone 6, for example, has a TDP rating of 20 watts. If these chips really are only producing 5 watts of heat, then they could probably even get away with running them without heat sinks, let alone fans.

 

[jdcranke07]

@cub: That might be true only if you are using another computer to charge the one you have as well as transferring data. You're rending the port useless if you are using the power cord to charge it and then trying to do data transfer via the power charger into the wall. Granted, they have not said if there will be a splitter in the power charger that would allow for hooking up to other devices.

 

[cub_fanatic]

@cub: That might be true only if you are using another computer to charge the one you have as well as transferring data. You're rending the port useless if you are using the power cord to charge it and then trying to do data transfer via the power charger into the wall. Granted, they have not said if there will be a splitter in the power charger that would allow for hooking up to other devices.

Yeah, I figured it would be a splitter or a hub (see Macbook type-c dongle outrage: http://gizmodo.com/heres-the-80-dongle-you-need-to-use-the-new-macbook-wi-1690351477). Hopefully, Windows laptop makers will have more sense (and compassion on our wallets) than Apple and include more than one USB port on their new machines.

 

[jdcranke07]

@cub: That might be true only if you are using another computer to charge the one you have as well as transferring data. You're rending the port useless if you are using the power cord to charge it and then trying to do data transfer via the power charger into the wall. Granted, they have not said if there will be a splitter in the power charger that would allow for hooking up to other devices.

Yeah, I figured it would be a splitter or a hub (see Macbook type-c dongle outrage: http://gizmodo.com/heres-the-80-dongle-you-need-to-use-the-new-macbook-wi-1690351477). Hopefully, Windows laptop makers will have more sense (and compassion on our wallets) than Apple and include more than one USB port on their new machines.

If they're smart they will, otherwise I foresee stocks dropping a bit. Apple has never been the company to really care about the wallet though. They've always been more of a company that focuses on people that are willing for fork out the cash and nowadays it's about the fad as well. "My friend has an Apple, so I need one" type of thing. This is especially true on a college campus. Anyways, Microsoft already kind of screwed up before Apple did. They have a low powered USB port on their Surface Pro 3 which in most cases can't run optical drives or most accessories unless the items are considered low power. This killed some of our Surface Pro 3 sales at my IT Store.