290 xFire on Z87 chipset using 1st and 3rd PCI Express Slots

[Attic]

To get better space between a crossfired 290 setup on a Z87 board (specifically either the MSI Z87 G45 gamer or G55) is their a substantial performance hit with running the 290's in PCI Express 3.0 16x slot 1 and 3 vs slot 1 and 2?

From my understanding using PCI Express slot 1 and 3 would run PCI Express 3.0 x8 and x4 instead of x8 x8 ( slot 1 and 2).

I'm hoping using slot 1 and 3 would be roughly equivalent to pci express 2.0 x8 x8 crossfire configuration, which is AFIAK just fine for 290/x bridge-less crossfire.


With the bridgeless function of the cards when run in crossfire it would be nice to take advantage of moving the second card down another inch or so, but i'm not finding much info regarding this setup. The manufacturers reccomend using the first and 2nd pci express slots, but I think i'd get a quieter and much cooler setup if didn't use the 2nd pci express slot at all in a 290 crossfire setup.

 

[Skurge]

There really isn't a need to run them so far apart. My cards ran pretty cool when I had them in the 1st and 2nd slots.

 

[Attic]

I'm considering the Powercolor PCS 290 which is a a bit thicker than others and concerned about lack of airflow with these specific models to the top card when run in xfire.

I will probably pay n pray.

 

[Attic]

Tests of PCI 2.0 and 3.0 at x8 and x16

Good look at performance of using different PCI-E speeds for single and dual gpu at 1080p and 4kUHD in that evaluation for anyone interested.

Still nothing i've found showing explicity a PCI-E 3.0 x8 with PCI-E 3.0x4, but hopefully there's no curveballs in that setup vs what the article shows for PCI-E 2.0 x8 for crossfire.

 

[wand3r3r]

I've been running mine in the G45 Gaming in the first 16x slot and the last 16x (4x?) slot.

Edit: I'll try BF4 now

Ok, so I use the two furthest apart slots as you mentioned. It works fine, I don't have hard data to compare though. I've been using it in that configuration for about a month and I just fired up BF4 to ensure I have tried it with that configuration. I tried BF4, 16x slot and 4x slot, with 14.2 drivers and it worked well. My FPS are absurdly high since I have 290x crossfire on a fairly low resolution screen atm.

PCI-E 3 4x should be PCI-E 2 8x speed. I don't think it will limit the cards in any way.

The one thing is that the card overhangs the MB a bit when you use that last slot. If you are in a tight case that may be an issue.

 

[Attic]

I've been running mine in the G45 Gaming in the first 16x slot and the last 16x (4x?) slot.

Edit: I'll try BF4 now

Ok, so I use the two furthest apart slots as you mentioned. It works fine, I don't have hard data to compare though. I've been using it in that configuration for about a month and I just fired up BF4 to ensure I have tried it with that configuration. I tried BF4, 16x slot and 4x slot, with 14.2 drivers and it worked well. My FPS are absurdly high since I have 290x crossfire on a fairly low resolution screen atm.

PCI-E 3 4x should be PCI-E 2 8x speed. I don't think it will limit the cards in any way.

The one thing is that the card overhangs the MB a bit when you use that last slot. If you are in a tight case that may be an issue.

I've got a Thor V.2 case that is a beast for xFire the 290/x's. I'll need to figure out something else for my HTPC case becaused i'd love to get that going with dual 290x for 4kHD,... but that will be a blast furnace unless I drastically change my current enclosure space for the setup.

Thanks for posting your results. If you ever get a chance to bench between 1 and 2 slots vs 1 and 3 slots please update thread. From reading I wouldn't be surprised if it was slight faster or slightly slower, but i'd be surprised if there was a substantial difference benefiting either setup.