2 PCI slot MB - difference between Crossfire vs Non Crossfire???

[Bongbuster]

Hi, I have no idea about motherboards that use two graphics cards so I need help bad

My situation is I need a PC that can run 3 or 4 monitors at the same time. For example I can display a different application on each monitor.

I know you can get MB's with two PCI slots such as gigabyte 785gt-ud3h which I am (was) planning on buying. I've also found out that you can two cards in a crossfire configuration on a crossfire compatible MB like the gigabyte ma790fx-dq6.

I find this confusing so i have some questions.

1-Can two graphics cards in crossfire configuration run 3 to 4 monitors like I want?
2-If you have two graphics cards that are not in a crossfire configuration and are only running monitors off one of those cards, the second card will not be used will it? (stupid question but want to make sure)
3-Which type of 2 PCI slot MB is normally more expensive, the crossfire compatible or the non crossfire compatible?

 

[Mussels]

crossfire is to enable two video cards to render a game faster than one video card.

Crossfire does not allow more than 2 monitors (off the master card)

Crossfire is not a requirement to run two video cards for four monitors.

With crossfire off, teh second card will only be used for whatevers connected to it. If you game on a screen off it, it will be the one used to render it.

You rarely get boards with two PCI-E slots unless they are crossfire or SLI comaptible.

 

[Bongbuster]

crossfire is to enable two video cards to render a game faster than one video card.

Crossfire does not allow more than 2 monitors (off the master card)

Crossfire is not a requirement to run two video cards for four monitors.

With crossfire off, teh second card will only be used for whatevers connected to it. If you game on a screen off it, it will be the one used to render it.

You rarely get boards with two PCI-E slots unless they are crossfire or SLI comaptible.

Thanks Mussels

So with crossfire off, can you run two monitors of the primary card and two monitors of the secondary card and display a different window/application on each of the four monitors?

 

[Mussels]

Thanks Mussels

So with crossfire off, can you run two monitors of the primary card and two monitors of the secondary card and display a different window/application on each of the four monitors?

yes.

you dont mention your operating system, but make sure you stick with similar cards - vista and 7 only allow one active video card driver at a time, so mixing ATI and nvidia for example, wont work. (or mixing an old ATI card and a new ATI card - since the latest drivers for the new card may not support the old one)

 

[Bongbuster]

yes.

you dont mention your operating system, but make sure you stick with similar cards - vista and 7 only allow one active video card driver at a time, so mixing ATI and nvidia for example, wont work. (or mixing an old ATI card and a new ATI card - since the latest drivers for the new card may not support the old one)

Thanks again Mussels.

I understand the cards need to be similar and I'd probably buy two 4830 cards or the next model up.

What confuses me is the motherboards that will support crossfire. I've had a look the ATI website http://ati.amd.com/technology/crossfire/faq.html but that lists chipsets not motherboards. I want to go to my local PC market, give them a couple of motherboard names and get prices from them. Don't know how to use chipsets.

I was given a price for the gigabyte 785gt-ud3h motherboard last Sunday but it does not support crossfire.

Basically I'm after a crossfire compatible motherboard that supports AMD Phenom II x3 720.

What is a simple way of determining which motherboards support cross fire and this CPU?

Is there a list some where of motherboards that support crossfire?

 

[unibrow1990]

Any motherboard with an amd chipset and 2 or more pci-e slots will support crossfire. also most motherboard say right in their descriptions whether they support crossfire or not since its a selling point.

 

[Bongbuster]

Any motherboard with an amd chipset and 2 or more pci-e slots will support crossfire. also most motherboard say right in their descriptions whether they support crossfire or not since its a selling point.

Hi unibrow1990, you are correct.

Looking over the specs after reading your post, I saw the crossfire support.

My reason for thinking that mother board did not support crossfire was the placement of the two PCI slots.

If you look at the pic here http://www.gigabyte.com.tw/Products...px?ProductID=3154&ProductName=GA-MA785GT-UD3H

you can see there is a big gap between the PCI slots. Can't work out how the bridge will fit over such a large gap.

 

[Mussels]

Thanks again Mussels.

I understand the cards need to be similar and I'd probably buy two 4830 cards or the next model up.

What confuses me is the motherboards that will support crossfire. I've had a look the ATI website http://ati.amd.com/technology/crossfire/faq.html but that lists chipsets not motherboards. I want to go to my local PC market, give them a couple of motherboard names and get prices from them. Don't know how to use chipsets.

I was given a price for the gigabyte 785gt-ud3h motherboard last Sunday but it does not support crossfire.

Basically I'm after a crossfire compatible motherboard that supports AMD Phenom II x3 720.

What is a simple way of determining which motherboards support cross fire and this CPU?

Is there a list some where of motherboards that support crossfire?

the reason being is that while there is only a handful of chipsets, there is thousands of motherboards using those chipsets.

you can always go the shop with a list of chipsets and they can find out via that - gigabyte boards for example, its part of the name

 

[unibrow1990]

If you look at the pic here http://www.gigabyte.com.tw/Products/...A-MA785GT-UD3H

you can see there is a big gap between the PCI slots. Can't work out how the bridge will fit over such a large gap.

The gap is that big so that you can fit a dual slot card in the first port without blocking the other port, the crossfire bridge will reach between cards in those ports without a problem.

 

[ToTTenTranz]

Actually, the 785G board you mention already has a GPU that supports two monitors (DVI+HDMI, DVI+D-Sub, D-Sub+HDMI).

So with that board, you'll only need one extra graphics card to get 3 or 4 monitor output.

That said, you're better off getting a single HD4890 for better performance than two HD4830s in Crossfire.

 

[unibrow1990]

Actually, the 785G board you mention already has a GPU that supports two monitors (DVI+HDMI, DVI+D-Sub, D-Sub+HDMI).

So with that board, you'll only need one extra graphics card to get 3 or 4 monitor output.

That said, you're better off getting a single HD4890 for better performance than two HD4830s in Crossfire.

Actually the igp will get disabled when he puts in a regular graphics card so he will need two external cards.

 

[ToTTenTranz]

Actually the igp will get disabled when he puts in a regular graphics card so he will need two external cards.

In my system (790GX) I have two HD4890s in Crossfire plugged to a 24" monitor, and the IGP is controlling two 17" monitors.

Disabling the IGP might be the default action in the BIOS, but I'm sure you can use the IGP and the external GPUs at the same time.

 

[Mussels]

Actually the igp will get disabled when he puts in a regular graphics card so he will need two external cards.

not true with AMD.

I can - and have - stuck another card in my 780G system (radeon 3450) and it stayed enabled and i could use both video cards - i could even crossfire them.

 

[unibrow1990]

My bad, I though it always turned itself off when you put in another card.

 

[Mussels]

My bad, I though it always turned itself off when you put in another card.

thats normal yeah. AMD have made an exception with their latest IGP's

 

[Bongbuster]

You guys are fantastic. I've found out from your help that the MB i'm interested in is cross fire compatible AND that the built in GPU can be used with an external GPU. The last time I built a PC (too long ago), you had to turn the IGP off in bios if you wanted to use an external GPU.

Now just have to decide whether to get two GPU's or get one and use the IGP; which GPU or set of two to buy.

This guide on the best GPU's for money in August is interesting http://www.tomshardware.com/reviews/best-graphics-card,2387.html

May wait till October when the 5000 series comes out and see if that drops the prices of the 4800 series.

Thanks alot once again for every ones help.

 

[sean]

I'm not sure I understand this. I have this Mobo....

ASUS M3A78-CM

http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=4016440&csid=_25

It sez it supports crossfire, yet it only has ONE PCIE 2 slot. So if I buy THIS Vid card.....

Visiontek Radeon HD 3650 OC Video Card

http://www.tigerdirect.com/applicat...1&csid=ITD&recordsPerPage=5&body=#ReviewStart

What would I hitch it up to in order to get "crossfire" being that there is only one PCIE-2 slot.

I'm just slightly confused here. Any advice would be greatly appreciated.

 

[ToTTenTranz]

Crossfire on that board means pairing an external PCI-Express graphics card with the board's integrated GPU.

That said, the 780G only supports Crossfire with a HD2400 or a HD3400 external graphics card.

Pairing with a HD3650 or superior would only slow down the overall performance due to the performance difference between the GPUs so it's not supported.

 

[wahdangun]

You guys are fantastic. I've found out from your help that the MB i'm interested in is cross fire compatible AND that the built in GPU can be used with an external GPU. The last time I built a PC (too long ago), you had to turn the IGP off in bios if you wanted to use an external GPU.

Now just have to decide whether to get two GPU's or get one and use the IGP; which GPU or set of two to buy.

This guide on the best GPU's for money in August is interesting http://www.tomshardware.com/reviews/best-graphics-card,2387.html

May wait till October when the 5000 series comes out and see if that drops the prices of the 4800 series.

Thanks alot once again for every ones help.

yep with HD 5870 you can get 5 monitor setup (3 from HD 58XX+2 from onboard) and stil have the performence of 2 HD 4870 CF

 

[sean]

So i guess the limiting factor here is that I do not have 2 PCIE-2 slots on my mobo?

 

[ToTTenTranz]

So i guess the limiting factor here is that I do not have 2 PCIE-2 slots on my mobo?

That chipset doesn't have separate sets of PCI-E lanes like the 790GX for example, so it wouldn't matter if it had a second PCI-E 16x slot.

 

[Soylent Joe]

Wow, I didn't know some of that stuff. So I could put my 4670 in with my 4870, while not enabling crossfire, in order to run 3 or 4 monitors.

 

[sneekypeet]

Wow, I didn't know some of that stuff. So I could put my 4670 in with my 4870, while not enabling crossfire, in order to run 3 or 4 monitors.

yes, and the fact of the matter is it will even work with two ATI cards on an SLI motherboard. Doesnt have to be crossfire or SLI specific to the GPU branding, just that the board supports 2 PCI X16 slots (or X8's)

 

[Soylent Joe]

So, I asked some person this today, could I run two Nvidia cards in SLI on my motherboard?

 

[sneekypeet]

There are a few working on modded SLI drivers that allow SLI on intel chipsets. I used it on the 7 series cards on an ABIT 975X....worked for a bit, in the end it failed, but things are looking up in the thread here. http://forums.techpowerup.com/showthread.php?t=60844

Technically the answer is no, but you can run 4 monitors off two NV cards on that board, just like the two 850XTPE's I ran on my SLIDR