Crossfire between PCI-E 3.0 x16 and PCI-E 2.0 x4

[Ahmadovich]

hey,guys

I have a R9 270 dual-x OC
and I'm gonna buy a new Mobo which is gonna support crossfiring 2 of that GPU in the future

but I noticed something while checking
the specifications of the GA-B85-HD3

they say it got
1 x PCI-E 3.0 x16 slot
1 x PCI-E 2.0 x16 slot (running at x4)

Assuming that the performance
of one R9 270 in the PCI-E 3.0 x16 is100%

if I added another one in the PCI-E 2.0 x4
how will the performance be if I did that ?
will it be 150% 170% 200% ?

and thanks

 

[Brantyn Gerik]

crossfire doesnt scale perfectly, but you will get slightly slower speeds from the 2.0 slot. Sooooo get a better motherboard that will let you run crossfire at 3.0 and at least 8x on each slot

 

[Brantyn Gerik]

also that motherboard nowhere says specifically that it supports crossfire

 

[aevm]

hey,guys

I have a R9 270 dual-x OC
and I'm gonna buy a new Mobo which is gonna support crossfiring 2 of that GPU in the future

but I noticed something while checking
the specifications of the GA-B85-HD3

they say it got
1 x PCI-E 3.0 x16 slot
1 x PCI-E 2.0 x16 slot (running at x4)

so let's say that the performance of one R9 270
is 100% in the PCI-E 3.0 x16.

if I added another one in the PCI-E 2.0 x4
how will be the performance if I did that ?
will it be 150% 170% 200% ?

and thanks

120%? 140%? I've seen charts about this scenario and they weren't pretty. In some games you would get something from your second card, in others very little. Don't try it. Get a MB that says x8/x8 and supports Crossfire officially.

 

[Ahmadovich]

crossfire doesnt scale perfectly, but you will get slightly slower speeds from the 2.0 slot.

thanks for answer
but I need you to tell me how will the performance be by Numbers language
Assuming that the performance of one R9 270 in the PCI-E 3.0 x16 is100%

also that motherboard nowhere says specifically that it supports crossfire

they say here
http://www.gigabyte.com/products/product-page.aspx?pid=4566#sp
Support for AMD CrossFire™ technology

 

[Ahmadovich]

120%? 140%? I've seen charts about this scenario and they weren't pretty. In some games you would get something from your second card, in others very little. Don't try it. Get a MB that says x8/x8 and supports Crossfire officially.

they say here
http://www.gigabyte.com/products/product-page.aspx?pid=...
Support for AMD CrossFire™ technology

 

[Ahmadovich]

Sooooo get a better motherboard that will let you run crossfire at 3.0 and at least 8x on each slot

it's money issue ,buddy

 

[aevm]

LOL, I'm not the one who said "at least 8x on each slot". With Z87 your choices are 16x+0x or 8x+8x, by the way.

 

[Ahmadovich]

LOL, I'm not the one who said "at least 8x on each slot". With Z87 your choices are 16x+0x or 8x+8x, by the way

what ?! 😀

 

[aevm]

Try this one
ASRock Z87 Extreme3 $115
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157372

 

[Ahmadovich]

Try this one
ASRock Z87 Extreme3 $115
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157372

I can't. it's money issue as I said before
----------------
back to the GA-B85-HD3
is it okay crossfiring on this board as Gigabyte says here ?

and if it's okay how much performance I will lose because of the pci-e 2.0 x4
is it slight loss or significant loss ?

as you see

this image is comparing the difference of performance of GTX 680 on different slots
and there is only 12% Performance loss
between it on PCI-E 3.0 x16 and on PCI-E 2.0 x4

I want the same comparing but
between a R9 270 on PCI-E 3.0 x16
and another R9 270 on PCI-E 2.0 x4
to know how much extra performance I will get if I crossfired them

thanks, I hope I'm not disturbing you

 

[leeb2013]

it says it supports Crossfire here http://www.gigabyte.com/products/product-page.aspx?pid=4566#sp

I tried by 7950 crossfire in the configuration you mention;

1 x PCI-E 3.0 x16 slot
1 x PCI-E 2.0 x16 slot (running at x4)

It lost about 10% of the performance compared with using two PCI-E 3.0 x8 slots, so nothing to worry about if you can't upgrade your mobo.

 

[themaskofwraith]

it says it supports Crossfire here http://www.gigabyte.com/products/product-page.aspx?pid=4566#sp

I tried by 7950 crossfire in the configuration you mention;

1 x PCI-E 3.0 x16 slot
1 x PCI-E 2.0 x16 slot (running at x4)

It lost about 10% of the performance compared with using two PCI-E 3.0 x8 slots, so nothing to worry about if you can't upgrade your mobo.

Im no Expert, but i dont think there is going to be any performance loss at all.(maybe 2-3%)

as the chart mentioned by you,
GTX 680 looses 12% in PCI2.0 @4X speed. That means the 4X bandwidth is sufficient for 88% of 680.
And R9 270 performs 10%(+/- 2%) less of 680, so i think ull get 99% of 270's performance.

From my knowledge ,The 4X lanes struggles to keep up only with higher end card not with mid end or lower end.

Someone correct me if im wrong.

 

[leeb2013]

it says it supports Crossfire here http://www.gigabyte.com/products/product-page.aspx?pid=4566#sp

I tried by 7950 crossfire in the configuration you mention;

1 x PCI-E 3.0 x16 slot
1 x PCI-E 2.0 x16 slot (running at x4)

It lost about 10% of the performance compared with using two PCI-E 3.0 x8 slots, so nothing to worry about if you can't upgrade your mobo.

Im no Expert, but i dont think there is going to be any performance loss at all.(maybe 2-3%)

as the chart mentioned by you,
GTX 680 looses 12% in PCI2.0 @4X speed. That means the 4X bandwidth is sufficient for 88% of 680.
And R9 270 performs 10%(+/- 2%) less of 680, so i think ull get 99% of 270's performance.

From my knowledge ,The 4X lanes struggles to keep up only with higher end card not with mid end or lower end.

Someone correct me if im wrong.

I was just going off the tests I performed, benchmarking my two 7950s in different PCIe slots. My conclusion was; nothing to be worried about.