Question about pcie lanes and possible upgrade to i7-9700k

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jacoro1

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I currently have a 4 year old i7-5930k build that has been slowly losing performance and stability and I'm itching to upgrade. The i7-9700k looks like a good candidate since I mostly game on this system.

My biggest concern is that my current rig gives me 40 pcie lanes and it looks like the 9700 is limited to 16. I only use one GPU, but I do have 1 m.2 pcie SSD, 4 sata SSDs and 2 sata HDDs installed. I would like to eventually consolidate some of my smaller SSD's into another high performance pcie one, or possibly one of the optane 3dxpoint drives. Would the reduction in pcie lanes cause reduced performance with this kind of setup?

I am also unsure if my current PSU (corsair AX860) will be sufficient. I am considering upgrading to an RTX 2080ti, and these new CPUs seem power hungry especially when overclocked.

Thanks for your input
 
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The Original Ralph
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vMax

vMax

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Hi just to be clear on the latest Z390 Motherboard you have 24 PCIe lanes, you can install 1 x 16 GPU running at full speed, 1 x NVMe PCIe 3 x 4 full speed SSD and then at least 3 (maybe more as I know some are shared with the NVMe) other SSD's running of the SATA 6GB's ports.

https://www.anandtech.com/show/12750/intel-releases-z390-chipset-product-information

You can now pick up some very impressive NVMe M.2 SSD's which are very fast worth over 3000 reads and 2500 writes upto about 1TB though they would be a bit expensive. I picked up a 480GB one from ADATA at only £130..

Finally the AX860w has more than enough power...
 
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karenjoly

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The 9700k cpu itself provides 16 lanes .

The intel chipset provides 24

=40 lanes.

 
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jacoro1

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So if I'm reading this chart correctly, the 24 lanes provided by the chipset will all go through a DMI3 connection, which is only 4x pcie. If I were to install 2 4x pcie SSDs , they would have to share a single drive's worth of bandwidth along with all of my sata drives, lan, sound, and other peripherals. Does anyone know how much impact this has in practice? I realize not everything will be using that bandwidth at once.
 
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vMax

vMax

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Yep it would share and drop to x2....I believe. Not the end of the world as it is still fast enough...
 
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jacoro1

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Maybe I phrased my question poorly. I understand there are enough lanes on the chipset, but everything is going through a DMI3 connection to the CPU which has 3.9GB/s of bandwidth. Newer PCIe 4x SSD's max out around 3.5GB/s each. What happens when you have two of these drives running along with everything else? My current 5930k setup uses PCIe lanes from the CPU for it's m.2 x4 socket, so it doesn't create any bottleneck.

I will often be playing a game from one drive while downloading large files to another, while the OS and swap file are running on a 3rd drive and a 4th is serving media to a TV. My assumption is that the drives will run at full speed as long as they aren't active simultaneously, but I'm not sure of the mechanics when you max out the DMI bandwidth.
 
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The Original Ralph

The Original Ralph

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i can't speak to four M.2 NVMe drives active simultaneously but i can to three, on my MSI MEG Z390 board, with an i9-9900K - i had the same concerns as you when i built this rig, as i came from a i7-5960X on a X99 chipset with 40 lanes. I do a lot of video rendering and a few of the programs are core hogs, While the OS is running off one M.2, the program will be reading the video file on one M.2 and rendering it to a 2nd M.2. I was using the same setup on my X99 board.

I could not believe the drop in render times, depending on the program i'm running anywhere from 1/3 to 1/2 lower render time. I had recorded a few files render times before tearing down the X99 system and compared it to the new system once it was up & running. The faster render times i believe are mainly from the higher OC speed (4.9 vs 4.2 on the X99 board) but all i know, the lower PCI lane count has not affected performance negatively.

The OS M.2 drive is mounted on a M.2 to PCIe adapter card, the other two are mounted in dedicated M.2 ports on the board - there are 3 ports, but one of them dis-ables 2 of the six Sata ports, so i avoid that M.2 port. And i have four 4 TB HDDs installed, plus 2 Sata SSDs connected
 
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