Jump to content
Search In
  • More options...
Find results that contain...
Find results in...

Ok, a stupid PCI-E lanes question...

So, I have a question I feel I should already know the answer to, and even my Google-fu has failed in getting a coherent solution.

 

Basically, I'm looking to replace my motherboard , & the one I'm looking at has only 16x PCI-E slots. My current board is a Rampage VI Extreme, & has a single 4x. Why I'm replacing it is a whole other thread. I also don't have the board hooked up right now, or I'd just check it on a 16x slot.

 

What I do have, is a system that will be maxed out on PCI-E lanes in the future. I will be going SLI when 2080ti cards drop in price and more water cooled options are out there, so that's 32 lanes if both run at 16x each. I also have two nvme drives, so there's 8 more lanes. That's 40, which is max for my rampage VI extreme. However, I also have a PCI-E 4x Asus thunderbolt 3 card I would like to use.

 

So, if I plug a 4x PCI-E device into a 16x slot, does it still take up all 16 lanes, or does it dynamically adjust to however many lanes the device can utilize or board limits (like if you sli 3 way you don't get 16x16x16, you get 16x8x8 in many cases). If I do this, then I'll have 3 devices running at 16x, and with the 2 nvme drives, it'll be at 56 lanes.

 

I know my logic is wrong here, and it's probably way easier than I'm making it out to be, but brain.exe has stopped responding.

 

Help is much appreciated, thanks

Link to comment
Share on other sites

Link to post
Share on other sites

What CPU are you using?

 

extra PCIe lanes requirements on top of what the CPU can provide will be supplied by the chipset, so all these things will run properly

CPU: i7-2600K 4751MHz 1.44V (software) --> 1.47V at the back of the socket Motherboard: Asrock Z77 Extreme4 (BCLK: 103.3MHz) CPU Cooler: Noctua NH-D15 RAM: Adata XPG 2x8GB DDR3 (XMP: 2133MHz 10-11-11-30 CR2, custom: 2203MHz 10-11-10-26 CR1 tRFC:230 tREFI:14000) GPU: Asus GTX 1070 Dual (Super Jetstream vbios, +70(2025-2088MHz)/+400(8.8Gbps)) SSD: Samsung 840 Pro 256GB (main boot drive), Transcend SSD370 128GB PSU: Seasonic X-660 80+ Gold Case: Antec P110 Silent, 5 intakes 1 exhaust Monitor: AOC G2460PF 1080p 144Hz (150Hz max w/ DP, 121Hz max w/ HDMI) TN panel Keyboard: Logitech G610 Orion (Cherry MX Blue) with SteelSeries Apex M260 keycaps Mouse: BenQ Zowie FK1

 

Model: HP Omen 17 17-an110ca CPU: i7-8750H (0.125V core & cache, 50mV SA undervolt) GPU: GTX 1060 6GB Mobile (+80/+450, 1650MHz~1750MHz 0.78V~0.85V) RAM: 8+8GB DDR4-2400 18-17-17-39 2T Storage: 1TB HP EX920 PCIe x4 M.2 SSD + 1TB Seagate 7200RPM 2.5" HDD (ST1000LM049-2GH172), 128GB Toshiba PCIe x2 M.2 SSD (KBG30ZMV128G) gone cooking externally Monitor: 1080p 126Hz IPS G-sync

 

Desktop benching:

Cinebench R15 Single thread:168 Multi-thread: 833 

SuperPi (v1.5 from Techpowerup, PI value output) 16K: 0.100s 1M: 8.255s 32M: 7m 45.93s

Link to comment
Share on other sites

Link to post
Share on other sites

2 minutes ago, Radiolint said:

Basically, I'm looking to replace my motherboard , & the one I'm looking at has only 16x PCI-E slots.

 I will be going SLI when 2080ti cards

 

4x pcie in a 16x slot will use 4x

 

I don't think you can SLI in a 16x only motherboard/cpu because SLI requires at least 1 16x and all other connections be 8x, so X299 / ryzen / x399 only.

Ryzen 5 3600 stock | 2x16GB C13 3200MHz (AFR) | GTX 760 (Sold the VII)| ASUS Prime X570-P | 6TB WD Gold (128MB Cache, 2017)

Samsung 850 EVO 240 GB 

138 is a good number.

 

Link to comment
Share on other sites

Link to post
Share on other sites

2 minutes ago, Jurrunio said:

What CPU are you using?

 

extra PCIe lanes requirements on top of what the CPU can provide will be supplied by the chipset, so all these things will run properly

I'm on a 7940X

Link to comment
Share on other sites

Link to post
Share on other sites

The x4 device will use 4 lanes, but it's up to the motherboard to decide how many actual lanes will be reserved to the slot.

Some motherboards automatically slit an x16 into 2 x8 and therefore your second pci-e x16 slot will have 8 electrical lanes available out of which only 4 will be used by your device.

Other more high end motherboards may have a chip which acts like a network switch, it takes 16 lanes from the cpu and creates 32 or more lanes that are then split between slots .... for example something like  x16-x16-none-none  or x16-x8-x8-none  or x16-x8-x4-x4  ...

It may also depend on how many m.2 connectors you have populated etc ...

 

Note also that you may have slots which receive pci-e lanes from the chipset and not from cpu ... cpu has some number of lanes and chipset also creates a bunch of lanes, but between cpu and chipset, you have a limitation of around 4 GB/s

For example, the i9-9900k may advertise 44 pci-e lanes, but that's COMBINED ... 20 comes from cpu, 24 are created by chipset.

Link to comment
Share on other sites

Link to post
Share on other sites

2 minutes ago, Radiolint said:

I'm on a 7940X

so your TB3 card will run through the chipset. That's because CPU lanes are given to GPUs and PCIe storage first before other devices.

 

4 minutes ago, themctipers said:

 

I don't think you can SLI in a 16x only motherboard/cpu because SLI requires at least 1 16x and all other connections be 8x, so X299 / ryzen / x399 only.

Rampage 6 is for X299...

CPU: i7-2600K 4751MHz 1.44V (software) --> 1.47V at the back of the socket Motherboard: Asrock Z77 Extreme4 (BCLK: 103.3MHz) CPU Cooler: Noctua NH-D15 RAM: Adata XPG 2x8GB DDR3 (XMP: 2133MHz 10-11-11-30 CR2, custom: 2203MHz 10-11-10-26 CR1 tRFC:230 tREFI:14000) GPU: Asus GTX 1070 Dual (Super Jetstream vbios, +70(2025-2088MHz)/+400(8.8Gbps)) SSD: Samsung 840 Pro 256GB (main boot drive), Transcend SSD370 128GB PSU: Seasonic X-660 80+ Gold Case: Antec P110 Silent, 5 intakes 1 exhaust Monitor: AOC G2460PF 1080p 144Hz (150Hz max w/ DP, 121Hz max w/ HDMI) TN panel Keyboard: Logitech G610 Orion (Cherry MX Blue) with SteelSeries Apex M260 keycaps Mouse: BenQ Zowie FK1

 

Model: HP Omen 17 17-an110ca CPU: i7-8750H (0.125V core & cache, 50mV SA undervolt) GPU: GTX 1060 6GB Mobile (+80/+450, 1650MHz~1750MHz 0.78V~0.85V) RAM: 8+8GB DDR4-2400 18-17-17-39 2T Storage: 1TB HP EX920 PCIe x4 M.2 SSD + 1TB Seagate 7200RPM 2.5" HDD (ST1000LM049-2GH172), 128GB Toshiba PCIe x2 M.2 SSD (KBG30ZMV128G) gone cooking externally Monitor: 1080p 126Hz IPS G-sync

 

Desktop benching:

Cinebench R15 Single thread:168 Multi-thread: 833 

SuperPi (v1.5 from Techpowerup, PI value output) 16K: 0.100s 1M: 8.255s 32M: 7m 45.93s

Link to comment
Share on other sites

Link to post
Share on other sites

1 minute ago, themctipers said:

4x pcie in a 16x slot will use 4x

 

I don't think you can SLI in a 16x only motherboard/cpu because SLI requires at least 1 16x and all other connections be 8x, so X299 / ryzen / x399 only.

The rampage 6 extreme is x299, and 4way sli capable, and I believe reading manual it can do 16x16

Link to comment
Share on other sites

Link to post
Share on other sites

Thanks everyone, appreciate the quick help fixing my stupid brain lol

Link to comment
Share on other sites

Link to post
Share on other sites

GPUs can run at 8x with no performance impact.

NEW PC build: Blank Heaven   minimalist white and black PC     Old S340 build log "White Heaven"        The "LIGHTCANON" flashlight build log        Project AntiRoll (prototype)        Custom speaker project

Spoiler

Ryzen 3950X | AMD Vega Frontier Edition | ASUS X570 Pro WS | Corsair Vengeance LPX 64GB | NZXT H500 | Seasonic Prime Fanless TX-700 | Custom loop | Coolermaster SK630 White | Logitech MX Master 2S | Samsung 980 Pro 1TB + 970 Pro 512GB | Samsung 58" 4k TV | Scarlett 2i4 | 2x AT2020

 

Link to comment
Share on other sites

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share


×