Choosing the Right CPU (PCIe Lanes matter bro)

[Anna Fire]

Hi,

I've been looking at building a new PC for gaming and 3D Design/Rendering purposes. My build currently involves a GTX 1080 and a M.2 or U.2 NVMe boot drive (or two in RAID 0).

 

The i7-7700k seems like the best processor choice right now for gaming however it only supports 16 PCIe lanes. In order to future proof my rig, I want to be able to eventually move to a GTX 1080 SLI setup when prices drop over the next year or two. However, two GTX 1080s in SLI REQUIRE at least 16 PCIe lanes (2x8) to work which means that I cannot also have M.2/U.2 NVMe (x4, or in RAID 0 2x4). This means that if I want to consider any possible setup involving SLI and NVMe memory, I would have to move to one of the older i7-5820k or i7 6800k processors on the LGA 2011v3 socket. Is this the best recommended path forwards or will Intel be releasing new higher end chips over the next 6-8 months that have higher PCIe capacities to accommodate the growth of NVMe memory in the high end market?

 

Thanks for all the help!

(first post, go easy on me)

[genexis_x]

First question, why SLI? Some games don't even utilize it well.
Second, why not Ryzen?

11 minutes ago, Anna Fire said:

gaming and 3D Design/Rendering purposes.

If you are willing to spend a lot of money, you can wait for X299.

[Droidbot]

6 minutes ago, Anna Fire said:

 However, two GTX 1080s in SLI REQUIRE at least 16 PCIe lanes (2x8) to work which means that I cannot also have M.2/U.2 NVMe (x4, or in RAID 0 2x4).

*sad trombone plays*

 

Incorrect - the chipset shares a metric fucktonne of PCI-E lanes with the entire system, called HSIO lanes. 

The Z270 chipset shares 30 lanes with the system, and some manufacturers assign PCI-E X4, dual NVMe, Thunderbolt, etc with these lanes. NVMe SSDs run off the CHIPSET lanes, not the CPU's lanes. 

[HKZeroFive]

No, no, no. The CPU itself offers 16 PCIe lanes dedicated to graphic cards. The Z270 chipset offers additional lanes on top of that for things like PCI cards and M.2 drives.

 

So you can have multiple M.2 drives without affecting the lanes for the graphic cards. Then again, don't RAID 0 because that only doubles the chance of data failure at no real benefit.

 

Here's a much more detailed explanation:

 

[Anna Fire]

Ahh this is that damn pebble I was looking for, I knew I was missing something. So the chipset has separate HSIO lanes that preform the function of PCIe lanes for NVMe memory, seems like I have some more learning to do! Thank you all!

[Droidbot]

Just now, Anna Fire said:

Ahh this is that damn pebble I was looking for, I knew I was missing something. So the chipset has separate HSIO lanes that preform the function of PCIe lanes for NVMe memory, seems like I have some more learning to do! Thank you all!

Well, HSIO is what is shared by the chipset - there's 30 lanes, but 6 of them are used for various things on Z270, so there is 24 lanes total for use by the chipset. However, connections are bottlenecked by the x4 link from chipset to processor, so be careful for that. I'd suggest NOT raid 0'ing SSDs as well, for the reasons above.

[Anna Fire]

Just now, Droidbot said:

Well, HSIO is what is shared by the chipset - there's 30 lanes, but 6 of them are used for various things on Z270, so there is 24 lanes total for use by the chipset. However, connections are bottlenecked by the x4 link from chipset to processor, so be careful for that. I'd suggest NOT raid 0'ing SSDs as well, for the reasons above.

Do other chips like the 5820k escape the bottleneck from chip set to processor since they have a native 28 lanes instead of 16? The x299 looks interesting, does this bring any new factors to the table for consideration?

[Droidbot]

Just now, Anna Fire said:

Do other chips like the 5820k escape the bottleneck from chip set to processor since they have a native 28 lanes instead of 16? The x299 looks interesting, does this bring any new factors to the table for consideration?

X99 is older than Z2/170, and really shows it  - the connection from the chipset to processor is half the speed, and it only shares 8(!) lanes. However, you can put them on the CPU lanes and escape that. 

 

X299 is very, very much an unknown at this point. 

[domandric034]

27 minutes ago, Anna Fire said:

Hi,

I've been looking at building a new PC for gaming and 3D Design/Rendering purposes. My build currently involves a GTX 1080 and a M.2 or U.2 NVMe boot drive (or two in RAID 0).

 

The i7-7700k seems like the best processor choice right now for gaming however it only supports 16 PCIe lanes. In order to future proof my rig, I want to be able to eventually move to a GTX 1080 SLI setup when prices drop over the next year or two. However, two GTX 1080s in SLI REQUIRE at least 16 PCIe lanes (2x8) to work which means that I cannot also have M.2/U.2 NVMe (x4, or in RAID 0 2x4). This means that if I want to consider any possible setup involving SLI and NVMe memory, I would have to move to one of the older i7-5820k or i7 6800k processors on the LGA 2011v3 socket. Is this the best recommended path forwards or will Intel be releasing new higher end chips over the next 6-8 months that have higher PCIe capacities to accommodate the growth of NVMe memory in the high end market?

 

Thanks for all the help!

(first post, go easy on me)

Get Ryzen 1700 or 1600X with X370 board

[Anna Fire]

7 minutes ago, Droidbot said:

X99 is older than Z2/170, and really shows it  - the connection from the chipset to processor is half the speed, and it only shares 8(!) lanes. However, you can put them on the CPU lanes and escape that. 

 

X299 is very, very much an unknown at this point. 

It sounds like I can either go with a i7-7700k or wait till the X299 release in order to determine if I would be willing to go that route (Since the i7-5820k and the i7 6800k are both on the X99 chipset). Do you know of any references for where I can learn about bottlenecks for 3D Design/rendering using products such as Autodesk, Inventor, Solidworks, NX, ect.? 

[mariushm]

AM4 has 24 pci-e v3.0 lanes.

 

* 16 are reserved for video cards (1x16 or 2x8 for processors without integrated graphics, or 1x8 exposed to motherboard for those with integrated graphics)

* 4 are dedicated to m.2 AND/OR 2xsata 6gbps  - up to the manufacturer of motherboard if it uses all four in the m.2 connector or if it splits this x4 in 1 m.2 x2 and 2 x sata 6gbps (and if there's no m.2 inserted user could plug regular sata drives in connectors, adding m.2 on pci-e x4 disables then 2 ports)

* 4 are dedicated for the connection to chipset which is optional but everyone adds one

 

The CPU also has built in SOC which has 4 x usb 3.0 connectors built in besides the sata controller.

 

The chipset then works sort of like a pci-e switch, creating a lot of pci-e lanes from those pci-e v3.0 x4 connection, just like Intel chipsets create lots of HSIO or whatever they want to call them.

Here's a typical layout for a ryzen with x370 chipset:

 

 

Ryzen Chipset Differences					
 		X370	B350	A320	X300	A/B300
USB 2.0	6	6	6		
USB 3.1 G1	6	2	2		
USB 3.1 G2	2	2	1		
SATA	4	2	2		
SATA Express
(2x SATA III or 
2x PCIe 3.0)"	2	2	2		
PCI-e 2.x	8	6	4		
SATA RAID	0, 1, 10	0, 1, 10	0, 1, 10	0, 1	0, 1
Multi-GPU	Yes[1]	No	No	Yes	No
Overclocking	Yes	Yes	No	Yes	No

SATA Express can split, again, into 2x SATA III, 2x PCI-e 3.x, or can merge with PCI-e GP lanes to create a 4-lane PCI-e port.

[1] "Yes x8/x8 or multiplexed"