A8-3800's HD 6550D Cross-Fired with HD 6670

stevieboy21

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Apr 22, 2012
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I have set up Cross-Fire on a friend's computer using the AMD A8-3800's APU which has the HD 6550D (512mb DDR3) integrated graphics _with_ a discrete Diamond HD6670 (2GB DDR3) video card. The DVI is currently connected to the MoBo's DVI output. CCC indicates that the APU and the discrete card are being Cross-Fired. Gaming performance clearly indicates an improvement, including a benchmark I ran (before and after).

The discrete HD 6670 card more than likely out-performs the integrated 6550D chip. Therefore, would connecting the monitor to the discrete card improve the Dual Graphics performance? Is it possible to do this?
 
the short answer is: No, you will see no improvement, performance would suffer and you should no do it.

the reason is that hybrid-crossfire (what you're doing) only works when the monitor is plugged into the motherboard's ports. thus plugging it into the graphics card port forces you to disable crossfire, thus losing the performance you gain from the 6550D
 
Thank you very much for reading my question and responding to it very accurately.

Can you enlighten me as to why plugging my monitor into my discrete graphics card port would fundamentally disable crossfire?

 
actually, it's just that the drivers won't allow it. it has to do with the way things on your motherboard are wired and how the drivers are set up. basically, you go into BIOS, and set your graphics setting to "integrated" to use the graphics on your APU. THEN, you install your AMD drivers, and tell it to use crossfire, while allow it to call up your 6670 into action once something demanding, such as a game, launches.

if done the other way around, you would set your graphics setting to "discrete" in BIOS first, so that you'll get an image on your monitor from your graphics card. at that point, the AMD drivers won't give you the crossfire option anymore
 
Great info, I have a question relating to the OP's. My set up is similar, except it's an A10-5700 paired with a 6670 (1 GB GDDR5). I figured out the original question with a lot of trial and error, but now I would like to keep my TV hooked up to the hdmi port, and hook up a smaller monitor to a dvi port.

The reason is so I could watch netflix or dvd's on the tv, and use the other screen for stuff like browsing or email simultaneously. Can I do this? And if so, to both displays get hooked up to the mobo ports to keep hybrid crossfire, or would the tv stay on the mobo and the monitor go to the 6670 output?
 


with an A10-5700 you should be fine. go ahead and hook up the two screens.

for anyone who's wondering, according to AMD, their entire trinity series of APUs will support multiple monitors. the older generation, Llano, doesn't all do this (the top ones do, but it's a bit tricky)
 
This thread has been very useful in understanding the display port configuration for Dual Graphics mode and I hope it can expand a little further to cover what I need to know -

With a setup similar to the OP's (my APU is A10-5800K), what steps would be required to have both graphics ports enabled (onboard & discrete), if even possible at all?
 


As far as I know this is not possible. again, this is because the user is being forced to select between "integrated" and "discrete" video output in BIOS. there is no "both" option, therefore having video output from both the motherboard's ports (uses integrated GPU), and a discrete graphics card is not possible
 

That seems like a logical deduction. But I was hoping for some confirmation because in my mobo's bios, there's a setting for "Integrated Graphics Device" which allows me to choose between "Auto", "Disabled", or "Dual Graphics", and this setting remains available even when the other setting to choose between "integrated" or "discrete" has been set to "discrete" (in my mobo's bios this option is explained as "Select Primary Video Device that BIOS will use for output").

So I've been thinking that with "discrete" selected as the "Primary Video Device" and "integrated" set to "Dual Graphics", the "integrated" ports might still be active (since it has not been set to "Disabled" in bios) till only after activating the Crossfire option in Windows environment. Thus I would simply need to leave the Crossfire option deactivated in Windows to be able to use both "integrated" & "discrete" ports?

I don't have the discrete card yet, but my decision to buy one is resting solely on this matter.
Thanks.
 


Hmm, might be a mobo specific thing. I would suggest digging through your mobo's manual? an easy way is to find the online PDF manual and just use the ctrl+f function :)
 

Well, that was the first thing I did but had no luck finding any helpful info in the product manual (MSI mobo FM2-A85XA-G65), or on their website, or their support forum. That's why I've been scouring all over other relevant forums such as here for a more definite answer.

On AMD's site for Trinity APUs, it says at the bottom of the footnote:
"With AMD Radeon™ Dual Graphics, full enablement of all discrete graphics video and display features may not be supported on all systems and may depend on the master device to which the display is connected. Check with your component or system manufacturer for specific mode capabilities and supported technologies." http://www.amd.com/us/products/desktop/apu/mainstream/Pages/mainstream.aspx#8

Thanks for your insights though. Greatly appreciated.
 

You must've missed reading my mobo model earlier so here it is again -
Brand: MSI
Model: FM2-A85XA-G65

Thanks.
 
You ask a highly specific question pertaining to an architecture that is relatively new and not widespread; a question that would be better asked in AMD's support forums.
However, your mobo has both DVI and HDMI. Why can you not simply hook one type to your monitor and the other type to your TV?
 


I'm looking to use two HDMI ports actually - one to send 3D video (hdmi 1.4 format) to a 3D display, and the other to send HD audio (DTS HD MA / Dolby TrueHD) to a AVR which is not 3D capable.

Ok, will try asking in AMD's support forum too. Thanks.