SLI / CrossFire FAQs

[goonting]

Great post. I wonder when will be the HD3870x2 be included.

 

[Maziar]

Its included

 

[medjohnson77]

So Sorry guys,

I went a BFG 8800GTS 512Mb card, couldn't be happier!

 

[Maziar]

Glad to hear it mate

 

[Oh SoS]

Another thing to add:

Neither SLI or CrossFire will support the use of multiple monitors when enabled!

This means you will have to disable the feature in order to get multiple monitor display (and enabling or disabling the feature typically requires a reboot).

 

[4745454b]

You don't need to reboot to turn a second monitor on or off. From what a coworker says, you don't need to reboot to turn SLI on or off either. I don't know about the status of CF though.

 

[Oh SoS]

You don't need to reboot to turn a second monitor on or off. From what a coworker says, you don't need to reboot to turn SLI on or off either. I don't know about the status of CF though.

nope, you do not need a restart with CF, even my ancient setup does not need that, all you need to do is disable it through the CCC, i have to do it with certain games, well CoH and dawn of war only(damn relic) and also if i want to rotate my display to portrait mode as forums like toms display better especially when they get changed and don't expand to fill the damn screen.(hint, hint Toms.)

I said "typically"...heh.

I haven't owned an ATI card in over a decade, but I know from personal experience that disabling/enable SLI often requires a restart...it seems to be dependent on the amount of virtual memory & ram in use.
And for someone who tends to leave the computer running w/ anti-virus running 24/7, rebooting (and clearing the virtual memory & ram) is not necessarily a bad thing...just kind of annoying when I want to go from playing a game to watching a movie on my big screen.

 

[hassa]

Another thing to add:

Neither SLI or CrossFire will support the use of multiple monitors when enabled!

This means you will have to disable the feature in order to get multiple monitor display (and enabling or disabling the feature typically requires a reboot).

Crossfirex will support more then one monitor in CrossFire mode (sweeeeeeeeeeeeeet)

 

[Maziar]

First of all again thank you 4745454b and also strangestr anger for helping me in this thread.

http://www.anandtech.com/video/showdoc.aspx?i=3151&p=4

Aside from potential performance scalability, there is also the capability to support up to 8 monitors from one system with 4 graphics cards installed. While this isn't as universally desired, it could be something fun to play with. We don't currently have a platform solution that we can use to test this yet, but we will certainly test this when we are able.

 

[klobnitrones]

Can you have 4 or 2 HD3870's on a 790FX

 

[klobnitrones]

correction HD3870x2's

 

[Maziar]

http://www.hothardware.com/articles/R680_Has_Landed_ATI_Radeon_HD_3870_X2/?page=2

Also note that the 3870 X2 has only a single CrossFire edge connector along the top of its PCB. It has only one because the other connection is already utilized on the PCB. Although the Radeon HD 3870 X2 is equipped with a CrossFire connector, at this time drivers are not available that will allow end users to link two of these cards together for quad-GPU CrossFireX. Those drivers are coming though.

 

[Oh SoS]

So you'd have to get an AMD mobo and 4 cards to get mutli-monitor support out of CrossFire X?

I'll pass.
but at least I can get 2 cards and not have to deal w/ the stupid dongle anymore, yeah?

 

[Maziar]

Edited

 

[Maziar]

Edited again thanx to my good friend 4745454b

 

[Maziar]

Edited

 

[stoner133]

Well I found an error right off the bat. You say that CrossfireX requires a motherboard with four PCIe slots. This is not true, My Gigabyte GA-MA790FX-DS5 supports CrossfireX with only two slots. How? Well you can use two 3870X2 cards on this board and then you have CrossfireX.

There is also a DFI board with the 790FX chipset that supports CrossfireX and it only has three PCIe slots.

 

[circeseye]

a couple things to fix on your post. where you discribed all the cards in each series
1. the 3870gx2 is NOT 2 cards (like nvidea) . its 2 gpus on one card
2. you do not need a crossfire edition card with the 2xxx and 3xxx series cards all cards in the series can crossfire. if memory serves the 1950 i believe didnt need it eather but the 1900 and down does


other then the little fixes good post.

 

[stoner133]

circesey is correct, 1800 and 1900 series cards needed a Crossfire Master card and it connected to the second card with a Dongle cable between the two cards on the outside of the case. The did away with that with the 1950 cards.

The 3870X2 sort of works like two 1900's but instead it has the Crossfire chip between the two GPU's on the one card and this chip is identical to the chip used on the 1900 Crossfire Master card.

 

[Maziar]

1_3870X2 is like 2 cards attached to one so i am not wrong about that

2_Thanks for that i will fix it

 

[Maziar]

Edited

 

[nukemaster]

I have to agree with Maziar on this one....it IS 2 cards since if it was just 2 gpus on one card they would not need video ram for each gpu...just one set of ram for both.....they are just crossfire on a stick. so its JUST like nvidia.

 

[kpo6969]

I have to agree with Maziar on this one....it IS 2 cards since if it was just 2 gpus on one card they would not need video ram for each gpu...just one set of ram for both.....they are just crossfire on a stick. so its JUST like nvidia.

1 card

http://en.expreview.com/2007/12/16/r680-pcb-and-stock-cooler-leak-pics/

http://www.quantum-force.net/tutorials/T000000006/

 

[Maziar]

I think u misunderstood it
I meant HD 3870X2 itself is a single card but its actually 2 card attached to each other just like 7950GX2 which needs only one single PCI-E 16x to run

 

[4745454b]

I disagree with Maz and nuke. The 3870x2 has only one PCB, hence it is one card. The 9800GX2 has two PCBs, so it is two cards. You can argue against this all you want, but there is only one PCB.

In the grand scheme of things, who cares. Be aware that each uses SLI/CF, and each card has its own benefits/draw backs. Whether it is one card or two doesn't really matter that much.