# How to Crossfire



## kyleswitch

There are plenty of different places you can get information on ATI's Crossfire Set up, but I just wanted to put it all in one place for the users of this forum.  The reason it's only crossfire is because I use ATI cards, I have never used SLI with Nvidia.  I am not claiming to be a crossfire master, I just want to clear some things up for people that are new to it and interested where to start.

Yes, there is already an official post on Crossfire/SLI.  It is very helpful, but brief in some parts.  The link for it is here (all credit for it goes to Kornowski):  http://www.computerforum.com/134899-official-sli-cf-thread.html





ATI's Site

*Intro*
	ATI's Crossfire X set up is where you can have multiple GPUs, or Graphics Processing Units, on a single Motherboard.  If you are familiar with Nvidia, the Crossfire set up is the same as Nvidia's SLI (Scalable Link Interface).

*Motherboards*
	Your first step in putting together a Crossfire computer is to have a Motherboard that supports Crossfire.  Both AMD and Intel have boards that support the Crossfire Solution, but not all of them have multiple PCIexpress x16 slots.  Some give you the option of Crossfiring, but with one slot running at x16 and the other at x8.  This isn't a bad thing necessarily, but it will cut the performance of the card running at x8.

Boards for best Crossfire capability (things always change, but for the time being these are what you would pick form):

*AMD* 
790FX

*Intel* 
X58
X48

This link is for a list of every motherboard type that supports Crossfire technology:

*ATI Graphic Cards*
When picking a card you want to make sure it is Crossfire enabled, most are now-a-days, and only ATI graphics cards can do this.  A complete CrossFire system requires a MINIMUM of TWO CrossFire capable graphics cards.  Knowing that you need two cards to Crossfire, you must also have the cards in the same series.  For example you can crossfire two 4890s or a 4890 and a 4850.  You can't Crossfire A 4890 and a 5770 though.  When you try to crossfire a card with another card out of it's series they wont be compatible.




Official Chart from ATI

When you Crossfire you must match the memory speeds and engine clocks of the lower clocked card. To obtain ideal performance, graphics cards should be paired correctly.  So, you cannot have one card clocked higher than the other, they must match for the best results. 

*Power Supply Solution*
	Both ATI Graphic Cards you choose will have certain power connectors that it requires.  For example, if you had two ATI 5850s that required 2x 6pin connectors and your power supply only had  2x 6pin connectors, you couldn't power both of the cards. 2x 6 pin connectors for 2 cards = 4x 6 pin connectors, fun math!

	You could use Molex to PCIexpress adapters to solve your lack of PCI express adapters, but this isn't recommended.  I have noticed and from reviews, it doesn't supply efficient power.  Last, always check that your power supply has the right wattage and amperage to power both your cards.  Read the Specifications on your cards for a recommended Crossfire wattage and amperage.

*Crossfire Bridge*
	Once you have your motherboard, Graphics cards and the correct power supply you can connect your crossfire bridge.

This picture has a single crossfire bridge and that's all that is needed.




http://www.vistax64.comattachmentsg...nning-2-4870x2-crossfire-crossfire-bridge.jpg

This picture has two Crossfire bridges, which isn't necessary.  The second set of tabs on the cards, where another Crossfire bridge can go, is meant for hooking up a third or even fourth ATI card.




http://xtreview.comimagesx1950-procrossfire-2.jpg

Three-four card Crossfire set up




http://xtreview.com/images/crossfire hd 4850 3 and four cards 02.jpg

*Multiple Displays*
You can use Crossfire with multiple displays as well.  Crossfiring allows you to hook up more displays than a single ATI card can.




http://www.gameguru.inimgati-eyefinity-technology-


This is a video that also gives a brief touch on everything I have been talking about.



Hope all of this helps and if you have any questions, comment and Ill write/send pictures back.

Cheers :good:


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## Theblackoutow

Great guide, I will soon crossfire my 5850 with another 5850, but it will have to run 8x, I just have to make sure my PSU has enough connectors for one more 5850.


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## kyleswitch

Nice 

I mentioned Molex to PCIe adapters, but like I said I don't recommend that unless you can't afford a new PSU.


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## lubo4444

Nicely done.


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## kyleswitch

doesn't seem like anyone finds this useful  oh well, hope someone can use it.


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## lubo4444

kyleswitch said:


> doesn't seem like anyone finds this useful  oh well, hope someone can use it.



It is useful.  It did help me clear few things that i wasn't sure about.


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## joh06937

we still don't have drivers that allow us to crossfire and run a 4-6 monitor setup, do we? i know it is promised but i am wondering if it came with the 10.1 drivers...


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## kyleswitch

I havn't tried it yet, but there is word of it.  Ill put some research into it and add it if I find something.  Anything missing from the guide that might be helpful to put in?


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## joh06937

nothing else i can think of. although you should make those crossfire pictures of hd 5870s or hd 5970s. those are way cooler looking than those you already have.


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## kyleswitch

So it is possible, I've just never seen it in action in real world (outside the company).

http://www.youtube.com/watch?v=7xIbgimB56k


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## Gooberman

kyleswitch sorry for off topic question, who's that person in your avatar!


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## joh06937

i am pretty sure that is just one of the unreleased 6-mini displayport cards.


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## joh06937

oh, you could mention the setting up profiles capability for eyefinity and regular desktop, although it really is buggy at the moment (mine takes like 4 clicks and black screens to finally go).


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## joh06937

oh yay, just turned "gold member!"


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## kyleswitch

Gooberman said:


> kyleswitch sorry for off topic question, who's that person in your avatar!



Comic con 09' Pikachu girl  go look her up

Ill expect you back in about 10 minutes... wash your hands when you're done...


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## Gooberman

naw i'm at school xD


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## kyleswitch

Gooberman said:


> naw i'm at school xD



That shouldnt stop you  haha, jk


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## kyleswitch

Bump, for knowledge


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## The Chad

Just to make sure, from your chart, if I read it right I can put a 5870 with a 5970?


What kinda powersupply do you recommend for something like tha?


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## kyleswitch

The Chad said:


> Just to make sure, from your chart, if I read it right I can put a 5870 with a 5970?
> 
> 
> What kinda powersupply do you recommend for something like tha?



Yes you can match a 5870 and a 5970.  Not that it matters, but a 5970 is essentially two 5870s.

This power supply would be great for Crossfire with those two cards.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011&Tpk=850hx


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## Theblackoutow

Could I crossfire with this PSU, would it be enough power/would I need a molex adapter?
http://www.tigerdirect.com/applicat...CODE=GOOGLEBASE&cm_mmc_o=VRqCjC7BBTkwCjCECjCE


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## kyleswitch

Are you trying to crossfire with another 5850, 5870 or 5970?

If you would crossfire two 5850s then you could but with molex connectors.  But for a 5970 your psu doesnt have enough power.  I am basing this off the wattage and you only have 50amp total off you two 12volt rails.

"650 Watt or greater power supply one 75W 6-pin and one 150W 8-pin PCI Express power connectors recommended (850 Watt with two 75W 6-pin and two 150W 8-pin connectors for ATI CrossFireX technology in dual mode)" - New egg (5970)


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## Theblackoutow

It was going to either be a 5870, or a 5850, but you said using a Molex connector was bad, what makes it so bad.


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## kyleswitch

Theblackoutow said:


> It was going to either be a 5870, or a 5850, but you said using a Molex connector was bad, what makes it so bad.



Not necessarily bad, just not as power efficient as PCI express connectors.  That's why they make PCIe connectors, or else they would just give you the option to put molex connectors on everything.


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## kyleswitch

bump for knowledge


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