MSI XPOWER AC Z97 - CPU with more than 16 PCIe lanes this mobo?

[jdj9]

Hello.

As per the manual of the MSI XPower AC Z97 motherboard, the SLI is supported at x16/x16 at PCI_E2 and PCI_E5. As far as i know, the Z97 generation of motherboards supports only CPU's that have up to 16 PCIe lanes and can run SLI configs at x8/x8. How is it possible that this mobo can run the SLI at dual x16 if there is no CPU in existence that supports it? I've checked every single CPU that is listed in the supported CPU's for this specific mobo and none of them supports more than 16 PCIe lanes.

Anyone knows why?

Thanks.
J.

 

[mcconkeymike]

No, it's got a PLX chip on the mobo. If you are running 1 GPU, you use the second slot which is a direct line to the CPU. If you are using multiple GPUs, you use the odd number slots which go through the PLX chip. It's a little complicated, but it allows CPUs with limited lanes to be able to run multiple cards at higher rates, either x16 or x8 for all.

 

[jdj9]

No, it's got a PLX chip on the mobo. If you are running 1 GPU, you use the second slot which is a direct line to the CPU. If you are using multiple GPUs, you use the odd number slots which go through the PLX chip. It's a little complicated, but it allows CPUs with limited lanes to be able to run multiple cards at higher rates, either x16 or x8 for all.

Thank you for shedding some light to this now it is starting to make sense!

So i got 2 more questions:

(1) Does the PLX chip makes a noticeable difference compared to a same generation mobo that does not have a PLX chip (assuming all components are exactly the same)? Basically what i am asking... does it work as advertised? 😀

(2) Do you think it makes a good difference in FPS if someone is using a Z97 motherboard that has a PLX chip (like this one) compared to an X99 2011-V3 motherboard that takes advantage of all the lanes, considering the below?

CPU: 4790k stock vs 5820k stock (or similar, as close as possible to 4790k)
Ram: DDR3 2400Mhz vs DDR4 2400Mhz
Same SSD on both systems
Same PSU
Same cooler
Same GPU's in SLI (for example 1070's)

(all components as close to each other as possible)

Thank you.
J.

 

[mcconkeymike]

PLX chips do add some latency between the CPU and GPUs, that's why there is normally a single slot that is a direct line from PCIe to the CPU for if you are only running 1 GPU. If you aren't planning on running 3 or 4 GPUs, I would not buy a mobo with a PLX chip, they really increase the price of the mobo. As for the difference between DDR3 and DDR4, there is some, but not much of a difference. There are several techs who've done direct comparisons on Youtube so you can check them out. Also I personally wouldn't even mess with SLI or Crossfire. Many games don't scale well or scale at all with multiple GPUs, you have to deal with extra heat, power consumption, and noise with a multi GPU setup. For the price of 2 1070s, just buy a 1080ti and call it a day and game your heart out. Oh and if you buy that powerful of a GPU, you'll want to make sure that you are running a high refresh 1440p monitor or 4k so that your GPU can really "stretch its legs". If you are gaming at 1080p then a 1060 6gb or a 1070 if you are running 1080p with a high refresh rate. Oh for your question about FPS between 5820k and 4790k, the 4790k will most likely have a better gaming experience since the 1150 CPUs have a higher clock and higher IPS than the 2011-v3 CPUs. If you are primarily gaming, you'll want to stick with mainstream Intel such as socket 1150 or 1151. If you are crunching numbers, coding, running a bunch of VMs, etc, then you might want a 2011-v3 or AMD Ryzen. I hope that helps.

 

[jdj9]

PLX chips do add some latency between the CPU and GPUs, that's why there is normally a single slot that is a direct line from PCIe to the CPU for if you are only running 1 GPU. If you aren't planning on running 3 or 4 GPUs, I would not buy a mobo with a PLX chip, they really increase the price of the mobo. As for the difference between DDR3 and DDR4, there is some, but not much of a difference. There are several techs who've done direct comparisons on Youtube so you can check them out. Also I personally wouldn't even mess with SLI or Crossfire. Many games don't scale well or scale at all with multiple GPUs, you have to deal with extra heat, power consumption, and noise with a multi GPU setup. For the price of 2 1070s, just buy a 1080ti and call it a day and game your heart out. Oh and if you buy that powerful of a GPU, you'll want to make sure that you are running a high refresh 1440p monitor or 4k so that your GPU can really "stretch its legs". If you are gaming at 1080p then a 1060 6gb or a 1070 if you are running 1080p with a high refresh rate. Oh for your question about FPS between 5820k and 4790k, the 4790k will most likely have a better gaming experience since the 1150 CPUs have a higher clock and higher IPS than the 2011-v3 CPUs. If you are primarily gaming, you'll want to stick with mainstream Intel such as socket 1150 or 1151. If you are crunching numbers, coding, running a bunch of VMs, etc, then you might want a 2011-v3 or AMD Ryzen. I hope that helps.

Thank you for your help. I actually do have a good Rig. 4790k, SSD, 2x1070 (FE), 16gigz @ 1866mhz