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Some questions about crossfire!

Last response: in Graphics & Displays
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October 12, 2013 11:54:50 AM

Heyhey!:) 

Before i start, my current setup is below (might have to scroll down). Also, im not english!:) 

I have been wanting to crossfire two GPUs for some time now. I have a overclocked sapphire 7950 card right now, and have been looking for getting another one.

1. First of all, is crossfire any good now? After searching, i have understood it was totally broken for some time, like many people actually did worse with crossfire than with only one. I saw something about some drivers that were gonna be released, but when googling, i find more about something not working than its actually working, hence why im asking.

2. I have a Asus Z-87C motherboard. Does that support crossfire? After a bit of googling, i have gotten mixed answers, everything from "it will work great" to "wont work, as the second doesnt deliver x16, only x8". It has 2 PCI slots for graphics cards which looks exactly the same.

3. I also have a 750w modular psu. Is this enough for dual GPU? Googling this i have also gotten mixed answers. Tried a bunch of calculators, which says everything from 550w to 1000w. Bear in mind i will also upgrade to 16gb ram later this year.

My setup:
Hard drives:1 2TB 7200RPM sata hard drive and 2 160GB IDE 54000RPM hard drives
DVD drives: 1 Ihas 524D and 2 older IDE DVD drives (cant remember the exact names)
CPU: i5 4670k with stock cooling
GPU: 1 Sapphire Radeon HD 7950
PSU: Corsair CX750W
Motherboard: Asus Z-87C
RAM: Corsair XMS3 8GB (2x4gb)
OS: Windows 8 64 bit

Thanks for reading, and if im missing anything crucial, i will answer my very best, i do have general knowledge when it comes to computers.

More about : questions crossfire

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a c 142 ) Power supply
October 12, 2013 12:42:39 PM

The PSU you have has only 2 x 6/8 pin PCIe power connectors I believe. Each HD 7950 will require 2. CF is much better now that the beta driver (13.10) has been released. I had a CF rig until lately; (2 x HD 7870/i7-875K). The Frame Pacing fix works great. Almost as smooth as Nvidia. But I believe your MB has x16, x4 bandwidth slots: http://www.asus.com/Motherboards/Z87C/#specifications
That would make it less than desirable for dual cards of that caliber.

So overall, I would avoid a 2nd HD 7950.
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October 12, 2013 1:35:17 PM

clutchc said:
The PSU you have has only 2 x 6/8 pin PCIe power connectors I believe. Each HD 7950 will require 2. CF is much better now that the beta driver (13.10) has been released. I had a CF rig until lately; (2 x HD 7870/i7-875K). The Frame Pacing fix works great. Almost as smooth as Nvidia. But I believe your MB has x16, x4 bandwidth slots: http://www.asus.com/Motherboards/Z87C/#specifications
That would make it less than desirable for dual cards of that caliber.

So overall, I would avoid a 2nd HD 7950.


Damn!

Well, my PSU has 2 8pin connectors (means it can give power to two gpus, as one of them gives power for one gpu). I did get 2 8 pin connectors with it, and i do have a 8 pin available.

Yup, i just saw the spesification site, so it looks like the other slot runs on PCIe 2.0, if im not wrong. Guess that settles it, no dual gpu for me.

Thanks anyways.
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a c 142 ) Power supply
October 14, 2013 10:11:34 AM

Just to clarify... It isn't the fact that the 2nd slot runs at PCIe version 2.0 that is the issue. It is the fact that the 2nd slot is only x4 electrically. The data path isn't there for keeping up with the first card when things get stressful.

The fact that the slot is Ver 2.0 is no problem, as today's cards still cannot exceed the bandwidth of 2.0 when running x8 or x16.
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