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3 Questions About 4850s in Crossfire

Last response: in Graphics & Displays
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May 22, 2011 2:27:36 AM

Currently I am using 2 monitors with one HD 4850. Since they are quite cheap now, and I don't really need a current gen card, I wanted to buy anouther 4850 and run them in crossfire. I have a few questions about it:

Most importantly, would I be able to plug in 3 or 4 monitors if I am using two cards, or am I only able to use one card for output?

Second, I know not all games support Crossfire, but I am looking more for OpenCL. Would OpenCL be able to utilize crossfire? 2 teraflops is a lot of power :D 

Third, I am using a 550w PSU and am running a P5E-Deluxe, Q9550 (overclocked), and 3 HDDs. Would it be able to power two 4850s? The eXtreme PSU Calculator says 509req/559rec at 100% load on all components, which is not an uncommon occurrence :-).

Specs:
Core 2 Quad Q9550 @ 3.4Ghz Stock Vcore
ASUS P5E-Deluxe (A.K.A. Maximus Formula)
ATI Radeon HD 4850
2x2GB G.Skill DDR2 1066Mhz
3-4 7200rpm HDDs
A bunch of USB Accessories
a c 175 U Graphics card
a b C Monitor
May 22, 2011 2:47:54 AM

AMD doesn't support 3 monitors over CF. You'll be stuck with only 2. I have no idea how well OpenGL works with CF.

As for the PSU question, probably not. Without knowing which PSU you have its hard to say. But you'll need one that can do at least 400W on the 12v rail, and probably more.
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May 22, 2011 2:07:57 PM

4745454b said:
AMD doesn't support 3 monitors over CF. You'll be stuck with only 2. I have no idea how well OpenGL works with CF.

As for the PSU question, probably not. Without knowing which PSU you have its hard to say. But you'll need one that can do at least 400W on the 12v rail, and probably more.


Thanks for the info. Too bad I have to upgrade to a newer generation to get 3 monitors :(  Also, I was talking about OpenCL, not OpenGL (which I don't care about much). My PSU is: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Before you say anything, I have never had an issue with it, and it runs completley cool and silent with a lot of load. I'm not sure what the wattage is on the 12v rail is though.

Sorry to get a bit off topic, but what would be a current gen equivalent (ATI or nVidia) to the HD 4850, since I don't need much more power than it has, and I don't want to spend $230 on a card.

[Edit]

I read this thread http://www.tomshardware.com/forum/272310-33-crossfire-m... and it seems that as long as I'm not trying to play games across 3 monitors (which i'm not) I can just toggle the crossfire off and use a 3 monitor desktop, and toggle it on when playing a game on only 1 monitor. Is this correct? Also, would the monitors be seamless, for example: dragging a video from one GPU to another? I just got a bunch of free monitors, and I want to find a way to use them :-).
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a c 175 U Graphics card
a b C Monitor
May 22, 2011 2:27:19 PM

For future reference your PSU claims to have 35A/420W.

The equivalent card would be the 5750. The 5770 would be like the 4870. No idea about CF and OpenCL.
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May 22, 2011 2:31:18 PM

4745454b said:
For future reference your PSU claims to have 35A/420W.

The equivalent card would be the 5750. The 5770 would be like the 4870. No idea about CF and OpenCL.


Thank you for that information. I read this thread http://www.tomshardware.com/forum/272310-33-crossfire-m... and it seems that as long as I'm not trying to play games across 3 monitors (which i'm not) I can just toggle the crossfire off and use a 3 monitor desktop, and toggle it on when playing a game on only 1 monitor. Is this correct? Also, would the monitors be seamless, for example: dragging a video from one GPU to another? I just got a bunch of free monitors, and I want to find a way to use them :-).
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a c 175 U Graphics card
a b C Monitor
May 22, 2011 4:30:36 PM

Correct. CF off and you should be able to use all three. I'm not sure if you have to unplug the monitor from the second 4850 when CF is on. It would be seemless. You'll be able to drag a window from one screen to the others like they are side by side.
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May 23, 2011 12:05:46 AM

4745454b said:
Correct. CF off and you should be able to use all three. I'm not sure if you have to unplug the monitor from the second 4850 when CF is on. It would be seemless. You'll be able to drag a window from one screen to the others like they are side by side.


Thank you for that confirmation. I didn't want to purchase another GPU just to find it wouldn’t work. 2 TFlops of rendering power! That will be awesome :D 
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a c 175 U Graphics card
a b C Monitor
May 23, 2011 1:14:21 AM

If you do anything to make use of that much power. My current E6600 with a 5750 is more then enough to handle TF2 and L4D2. I couldn't use it myself. Of course, and don't laugh, I'm upgrading tonight to an i5 750 and will soon get a new GPU, but I have a semi logical reason for that.
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May 29, 2011 1:16:50 AM

4745454b said:
If you do anything to make use of that much power. My current E6600 with a 5750 is more then enough to handle TF2 and L4D2. I couldn't use it myself. Of course, and don't laugh, I'm upgrading tonight to an i5 750 and will soon get a new GPU, but I have a semi logical reason for that.


Well seeing that TF2 was released in 2007, I'd hope my computer would be able to handle it. What about Crysys 2 :-)? I would be using it more for computing power, not games. I have not fully made up my mind yet though.
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May 29, 2011 1:17:37 AM

Best answer selected by polird.
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a c 175 U Graphics card
a b C Monitor
May 29, 2011 4:04:44 AM

Crysis two isn't that demanding. DX9 game that was designed for consoles. Crysis 1 on the other hand...
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a c 273 U Graphics card
a b C Monitor
May 29, 2011 11:07:03 AM

This topic has been closed by Mousemonkey
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