ASUS P8Z68 Deluxe Gen 3 / 2 GPU's non SLI

[Fakum]

In the midst of a new build,
GPU = i5 2500k
Mobo =ASUS P8Z68 Deluxe/Gen 3
Ram = not yet determined
OS = Win7 64 Ultimate
SSD = not yet determined
GPU = New HD 6970 for 30” Main Screen @ 2500 x 1600
Reusing an HD 5850 (I already own) for a 24” touch screen to run Helios

This is primarily a gaming rig to run Combat Flight Sim DCS A-10 Warthog. Based on this picture of the motherboard, (and they are both PCI-e 2.0 cards), there are (2) PCI-e 3.0 slots and (1) PCI-e 2.0 slot at the very bottom. I would think that I should use the very top PCI-e 3.0 slot for the new HD 6970 GPU, and the very bottom PCI-e 2.0 slot for the HD 5850 card, this will keep some decent spacing for airflow. I want to make sure that the configuration I am considering does not create a performance impact?



The following was a suggestion to me from over at the flight sim forums, and I do not have an answer to this,, any input would be appreciated.

“The one thing to look at really is how the controllers are set up, and I'm unfortunately a bit foggy on that. You'll get better performance if you ensure that the card sits in a position where it can be governed by the CPU's integrated PCIe controller as opposed to a controller on the mobo. I never checked if the CPU can switch which PCIe ports it'll talk to or if it is one specific.

This is obviously N/A if the CPU doesn't have a PCIe controller - in this case, a PCIe 3.0 port is obviously on the mobo. Not sure whether you'll actually notice the difference though.”

 

[Fakum]

Im embarrased,,, 54 views and not 1 comment,,, I musta screwed this question up,,,

 

[jameseboy]

The only impact you will notice is that the bottom pci slot (black) only runs at x4 instead of x16, but if your not going to run anything graphically intensive on it, then you wont have a problem. I have a gtx460 in my first slot running my 1920x1080 screen and an nvidia 7300gs in the bottom x4 slot running my 2 other screens. I use my main for gaming and the others for system monitors/skype.

 

[Theocnoob]

It'll definitely create an impact. More than anything on the 5850 on the 4X slot. Again it depends what you're running on it. If the 5850 isn't doing any 3D it won't matter.

 

[Fakum]

Thanks for the feedback, Im a bit confused at interpreting the specs then? I mean, it does say:

PCI Express 3.0 x16 (2 single @ x16 or dual @ x8)
PCI Express 2.0 x16 (1 @ x4)

I took the "PCI Express 2.0 x16" as 16 speed and had no idea what the "(1 @ x4)" was.

Im using the HD 5850 for a touchscreen running Helios, So I would imagine that tasking is heavy enough to task the card enough to warrent moving it to a PCI-e 3.0 slot instead? Either way, what will then happen if I then utilize both of the PCI-e 3.0 slots for the 2 different cards, do I then diminish the new HD 6970 performance because it may cut down the speed from 16 to 8 on both PCI-e 3.0 slots because I am using them both even though they are not hooked up in SLI or XFire (basing that thoery on (2 single @ x16 or dual @ x8) )?

 

[Theocnoob]

Ya it's telling you exactly what it has. It can not turn a slot that is 4X electrically into anything else. The CPU has 16 lanes and the PCH has a few lanes also that are mainly used for SATA, additional controllers for USB 3/storage, etc, and also for lower speed slots. You ideally only want your gpu(s) talking to the cpu, so you would put CPUs in the 8/8 slots. The cpu can either give you 16 lanes for one card or 8 and 8 across 2 cards.

You diminish the bandwidth for your card so yes you decrease its theoretical max performance. You don't notice much difference in gaming only a couple of FPS.

 

[Fakum]

Ya,, lost me a little,, but I think I understand? Bottom line is,, if I use both the PCI-e 3.0 slots, I will somewhat diminish the performance of the new HD 6970 card.

I also thought about this,, I was using the HD 5850 card in a Gigabyte GA-X38-DQ6 MOBO
http://www.legitreviews.com/article/581/1/
And I was fine with it, so I was tring to figure out at what speed it was running before? The specs simply say it was a PCI-e 2.0 x 16 slot,, I have no idea what speed though, so I dont really know if indeed that the bottom PCI-e 2.0 slot speed of the new MOBO is actually going to be diminishing? i cant find a way to compare old vs new PCI-e 2.0 speeds?

 

[Fakum]

T
Im using the HD 5850 for a touchscreen running Helios, So I would imagine that tasking is heavy enough to task the card enough to warrent moving it to a PCI-e 3.0 slot instead? Either way, what will then happen if I then utilize both of the PCI-e 3.0 slots for the 2 different cards, do I then diminish the new HD 6970 performance because it may cut down the speed from 16 to 8 on both PCI-e 3.0 slots because I am using them both even though they are not hooked up in SLI or XFire (basing that thoery on (2 single @ x16 or dual @ x8) )?

I am ready to build now but dtill not clear as to where to put these cards? Im now getting an HD 7870 for my main 30" monitor, and will be using my old HD5850 to run Helios on a 24" touchscreen. I dont want to diminish the performance of the new HD 7870. I hope I am asking this question so its clear as to what Im trying to accomplish? Thanks

 

[jameseboy]

put the 7870 in the first slot, this will set it to 16x.
put the 5850 in the bottom slot. It will set it to 4x and will not affect the performance of the 7870.

SandyBridge has 20 lanes outputting. in your case, 16 will go to the 7870 in the top slot.
the middle one will be empty and will use 0 lanes
the bottom will have your 5850 in it and will use the remaining 4 lanes.

 

[Fakum]

Thank you sir!

 

[Fakum]

Well!!! this really SUCKS!!! I have all the PC parts I need, I just havnt purchased the HD 7870 yet (holding out for a little better price). I put the rig together today,,, I CAN NOT install the radeon HD 5850 in the bottom PCVI-e slot, it simply blocks all the plug in header ports and Id have to pull all the front panel wiring out, it blockes every feature at the botom of the MOBO. (I have photos if I need to post)

So I understand correctly, if I put the new HD7870 in the top slot, and put the older HD 5850 in the middle slot, I diminish the performance of the HD 7870 correct?

So I migh actually be better off running both monitors off the HD 7870 then putting the 5850 in the middle?

I dont have the funding to X-fire 2 cards.

Another thing, if I am going to have to use 1 card only, am I better off going with AMD instead? (I dont recall if AMD supports 2 monitors?)

Any suggestions would be appreciated, thanks

 

[jameseboy]

ah yes, i never thought about that. The performance will dimish, but barely noticable. For running the 2 monitors, you could just use the 7870, when games ect load, the 2nd monitor loses most of the control to it, so your not going to see much of a degrade in performance if at all any. I have both my monitors plugged into my GTX460

 

[Fakum]

Im not sure if your familiar with Helios or not, but I planned on running DCS Warthog on the 30" monitor @ 2560x1600 using the HD 7870, and the 5850 for the 24" touchscreen for flight controls etc.

 

[jameseboy]

okay, probably best then to put your hd7870 in the top slot, and 5850 in the middle. The bandwidth difference shouldnt make much difference to you.

 

[Fakum]

So you think the performance would be better in that config vs using only the 7870 to run both? Thanks