PCI-E card layout (chipset or CPU)

[OxyPug]

Hi everybody!

 

Looking for some advice regarding laying out my PCI-E cards on my old Haswell system. I have three cards; an RX 570, a UAD-2 DSP card, and a Wifi/Bt card. Priority is on the RX570 and the UAD card. My mobo is a GA-z87x-UD3H and the processor is a Xeon E3-1246 v3. I have included the page of the manual with the block diagram which is what is informing my musings. 

 

With this in mind, where to place them? Obviously the RX570 gets the top/main slot, no debate there. According to the diagram, the slots I have left are;

 

A: connected directly to the PCI Express bus off the CPU.

 

B: connected to the PCI Express bus coming off the Z87 chipset.

 

I won't be using wired LAN so according the block diagram the card in B will be the only IO on that Bus. 

 

My thinking was to put the UAD-2 card on the CPU bus (A) as I assume it's the more reliable connection and the BT/WIFI card won't really care either way. 

 

Does this make sense? Anything I've missed. 

[Electronics Wizardy]

Id put the wifi and DSP card on the chipset lanes. They both don't need much bandwidth, so it won't matter. Might as well give the gpu a x16 slot since the other cards don't need it.

 

You can always test this for your self though, you got the hardware

[Somerandomtechyboi]

Off topic but fyi

 

Z87 boards seem to be able to bclk oc so if you wish to oc your xeon you can do it via bclk if you havent done that already

 

 

Since the chipset pcie lanes are also shared with basically everything else like usb and sata, you may wanna avoid putting too many sata drives or usb devices so your other pcie cards dont get starved of bandwidth, though just like the above reply said, test it yourself and see if you run into any bandwidth issues, and maybe even test how many usb and/or sata you can use before the cards start to get starved by banwidth

[OxyPug]

22 minutes ago, Electronics Wizardy said:

Id put the wifi and DSP card on the chipset lanes. They both don't need much bandwidth, so it won't matter. Might as well give the gpu a x16 slot since the other cards don't need it.

 

You can always test this for your self though, you got the hardware

That was my first plan, but according to intel the PCI-E config for this CPU is "1x16, 2x8, 1x8/2x4" which makes me believe I'll end up with it running at 8x regardless in this scenario. I may be misinterpreting what it means. 

 

18 minutes ago, Somerandomtechyboi said:

Since the chipset pcie lanes are also shared with basically everything else like usb and sata, you may wanna avoid putting too many sata drives or usb devices so your other pcie cards dont get starved of bandwidth, though just like the above reply said, test it yourself and see if you run into any bandwidth issues, and maybe even test how many usb and/or sata you can use before the cards start to get starved by banwidth

I'm going to be using all 6 SATA ports (going to be because I've had to move from my Z97 ITX build to this to fit the UAD), but only three drives need access when I'm in my music workstation OS. The audio interface is also USB but only 2.0 and it doesn't even saturate that bus. With music production it's less bandwidth (unless your using software instruments) and more latency and stability that are essential.  

 

As you two say I'll experiment, the case is a HAF XB so it's not exactly difficult to move the cards about! 

[OxyPug]

23 minutes ago, Somerandomtechyboi said:

Off topic but fyi

 

Z87 boards seem to be able to bclk oc so if you wish to oc your xeon you can do it via bclk if you havent done that already

Definitely interested, it runs so cool I would love to eek some extra performance out of it. This mobo has great VRMs and used to run a 4670K at 4.5GHz when the z97-wifi could barely keep it stable at above 4GHz. Do you have any resources you can point me to on bclk OC'ing?

[Electronics Wizardy]

17 minutes ago, OxyPug said:

That was my first plan, but according to intel the PCI-E config for this CPU is "1x16, 2x8, 1x8/2x4" which makes me believe I'll end up with it running at 8x regardless in this scenario. I may be misinterpreting what it means. 

If you use the x1 slots of the chipset x4 slot it won't affect the gpu performance at all.

 

 

[OxyPug]

17 hours ago, Electronics Wizardy said:

If you use the x1 slots of the chipset x4 slot it won't affect the gpu performance at all.

 

 

Ok, this is where I think I'm misunderstanding the CPU layout.

 

As I read "1x16, 2x8, 1x8/2x4" I interpret that to mean I can have 1 PCI-E card at 16 lanes if that's the only card. If I have two cards, the CPU can handle only two 8x cards at a time, and if I have three (as in my case) then I get one 8x slot and two 4x slots regardless of what the mobo is capable of as this is a CPU limitation. 

 

I realise now that it could be saying you get all of them together, and the breakdown is just the way they can be divided?

[Electronics Wizardy]

4 hours ago, OxyPug said:

Ok, this is where I think I'm misunderstanding the CPU layout.

 

As I read "1x16, 2x8, 1x8/2x4" I interpret that to mean I can have 1 PCI-E card at 16 lanes if that's the only card. If I have two cards, the CPU can handle only two 8x cards at a time, and if I have three (as in my case) then I get one 8x slot and two 4x slots regardless of what the mobo is capable of as this is a CPU limitation. 

 

I realise now that it could be saying you get all of them together, and the breakdown is just the way they can be divided?

That only applies to the top 2 x16 slots. The bottom x16(actually a x4) and all the x1 slots run off the chipset lanes and aren't affected by the sharing of lanes from the cpu.

[OxyPug]

6 hours ago, Electronics Wizardy said:

That only applies to the top 2 x16 slots. The bottom x16(actually a x4) and all the x1 slots run off the chipset lanes and aren't affected by the sharing of lanes from the cpu.

Ah! Ok, that makes a whole lot more sense. Thanks for helping me with understanding this. Got everything built back onto this board today and it all seems to be going smoothly. For now I've got them set up with my initial concept, will try to work out a way to roughly benchmark and then maybe try moving the DSP card further away from the 570 and the heat it produces.