SLI / CrossFire FAQs

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Maziar

Maziar

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Hello mate :)
No need to applogize for anything i am glad to help :)

Well your PSU is good for 2x HD 4870s.
Can you test both cards in single mode ? i mean take 1 card out and test with the other one and play some games and see if it works well or not.
 
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madass

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If the Corssfire thing doesn't show, does it mean the card is defective or is it a driver issue? And howw can it be fixed? I've read on the AD forum of some people having this problem.

Anyway, thanks for the fast reply....:)
 
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creepy_maverick

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THANK YOU Sir!

Ill try to do that!
 
Maziar

Maziar

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If it doesn't show,then there MAYBE a problem,update your drivers also check your FPS in games,if you are not getting good frames,then something must be wrong.
 
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madass

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Does the crossfire option come for all ATI X2 cards? I read on the AMD FAQ that it should not come at all...or is the 4850 a special case siince its not really a true X2?
 
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madass

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Thannks
 
Confused Stu

Confused Stu

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Damn, I feel stupid asking this but I don't know anyone else crossfiring and google hasn't been my friend on this occassion!

I've recently added a second 4870 onto my little rig, which is working fine. My problem is during boot up, both card's fans spin up for the POST then the card in the main slot quietens down to idle but the one in the second slot doesn't and stays loud. Once the Windows drivers load, the second card's fan quietens down to idle too and then it all works as expected from there.

The card in the second slot works fine when running on it's own (I ran it solo for several months before buying it a companion). I've examined the BIOS using the ATI Bios Editor and the fan speeds are identical for both cards.

My question is - is this normal under crossfire, that the motherboard/BIOS can only control one fan and the other fan isn't controlled until Windows kicks in? The only reason I'm worrying is that my motherboard has ExpressGate built in, so I can boot into a quick, tiny Linux build instead of Windows if I want, but the constant loud-ish fan noise from card 2 gets grating after a while.

I'm using an Asus P5Q-E with Q6600 (o/c to 3.4), Kingston 8GB DDR2-1066, XFX 4870 1Gb crossfired with Sapphire 4870 512Mb, 76Gb Raptor and 500Gb WD HDD, Hiper 880W Type-M PSU, Zalman CNPS9900, Antec 900 case and Vista 64. Currently running dual 20 inch 1600x1200 monitors.

Thanks for reading, and sorry it turned into a long post! :)
 
Maziar

Maziar

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If you can change your fan speed in windows then there is no problem here.
I'm not sure why BIOS only allows you to work with one of the cards fan speed,maybe a BIOS update allows it,as i said i'm not sure but as long as you can change the fan speed in windows then there is no need to worry :)
 
Confused Stu

Confused Stu

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Thank you for the quick response. :)

As you quite rightly pointed out, I can change the fan speed within Windows so I know that's not a problem. My problem lies BEFORE Windows boots up - does everyone's second card spin faster/louder, or is that just a quirk of my motherboard?

I know this sounds like nit-picking, but if I want to pop online for 10 minutes, it's quicker to use the built-in ExpressGate than wait for Windows to boot. http://en.wikipedia.org/wiki/Expressgate The problem there is that because I'm not booting into Windows, the fan on the second card never slows to idle so it's constantly running loudly while I'm in ExpressGate, which gets annoying!

Thanks again.
 
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madass

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I kinda agree-You will probably thrash the high end card completely around 70-80 % of the time.
 
Maziar

Maziar

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You didn't read the whole review ;)

2 midrange card sometimes beat 1 high-end card but not always,it depends on most settings(like drivers,resolutions and so)

 
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CKLayoka

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Question: Do two Graphics cards in CrossFire X on PCI-E x16 buses have to be right next to each other? For example, If you have two x16 buses separated by 1 standard PCI bus could you still use the non-adjacent buses for CrossFire?
 
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CKLayoka

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Yes, but how far away? Can the "band" that connects the CrossFire connectors stretch across 1 expansion slot, to connect with a Card in a slot not immediately next to it?
 
nukemaster

nukemaster

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Yes, some boards(P5W DH) have slots farther apart(to allow for better airflow or even 3 pci-e slots on some boards) and use a flexible or longer crossfire or SLI connector bridges that makes it easier to use if the cards are close or far.

I am sure there is a limit on how far they can go(losses.noise), but lets say you have

PCI-E x16 - Xfire/SLI card
PCI - covered by card as well
PCI-E x4 - Raid card
PCI-e X16 - Xfire/SLI card
PCI-covered by card
PCI-Sound card :0

Then a cable bridge should connect them with ease.
 
nukemaster

nukemaster

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By bridge I mean the connector from card to card.

Since some boards have there PCI-E slots only 2 slots away

PCI-E(Top Card)
PCI(Blocked)
PCI-E(Next Card))

Others have
PCI-E(Top Card)
PCI(Blocked)
PCI-E X4 Usable or left clear for cooling
PCI-E(Next Card)

There are different length bridge connectors. Maybe they are all longer and flexible now, so it may not matter anymore since a longer flexible one will do all configs. The one for my P5W is too long(and is a solid one) for some boards.
Something like this.

sli-connectors.jpg
 
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CKLayoka

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Okay, I get it now, thanks!
When you go to hook up your system to the monitor (with 2 graphics cards in CrossFire for example), do you just simply plug it (VGA DVI, ect.) in either card, or do you need some sort of Y cable (I've seen those in use in pictures)
 
nukemaster

nukemaster

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In the old days you had to connect the screen to the master card(To be honest, i am not sure about how it works now[Maziar can answer that one for sure :)], I guess the top card).

The external cable you saw was a cable ATI used to use to allow the slave card to send its images(partial/alternating frames) to the master card to have the images/frames incorporated(portions placed to make a full frame or alternating frames put in the right order) with a composting chip on the master card then sent to your screen for you to see.

http://www.tomshardware.com/reviews/ati-puts-nvidia,1047.html
 
Maziar

Maziar

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thanks for the tip about the CrosFire cable nuke :)

About hooking your system to the monitor,not sure about it,but when nuke says that it was needed to connect to the master card in order to work,and since newer cards like HD 48xx series dont have this slave/master card things,i think its safe to say you can connect it to either cards.
 
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awanghartawan

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how to setting crossfire X dual GPU in Ati 780V chipset with integrated HD3100 with discreet vga HD 4350 because when i tried to put them both nothing happened....is it within BIOS setup or maybe they just not fit to each other as crossfireX? can u help me...thanks
 
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