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afo
Adept I

4x HD5970 Support?

It is possible to work with 4 HD5970 in one system?

dear people,

I am not sure if this is the right forum to ask, so please apologize and direct me to the right place if not.

Currently I am working with 2x HD5970 for an openCL application, and I am using a MSI 790FX-GD70 motherboard. It has 4 PCIe slots and claims to support up to 4 graphic cards.

But the MSI web site says that when you use 2 PCIe slots, they are at 16x, but when you use 4 PCIe slots, the speed of each one is 8x.

(http://www.msi.com/index.php?func=proddesc&maincat_no=1&cat2_no=171&prod_no=1740)

So my question is: Can I work with 4x HD5970 at PCIe 8x (with a transfer speed penalty), or HD5970 can only work at PCIe 16x?

Thanks in advance for any insight about this

best regards,

Alfonso

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4 Replies
emuller
Journeyman III

4x HD5970 Support?

See these threads:

http://forums.amd.com/forum/messageview.cfm?catid=328&threadid=122135

http://forums.amd.com/devforum/messageview.cfm?catid=328&threadid=107726

http://forums.amd.com/devforum/messageview.cfm?catid=328&threadid=103174

In my experience, using a dual GPU card in a 8x slot is no problem (proved by putting 2 4870x2 in a 790fx system with a gtx260).  I would love if someone from AMD would correct me here, but all reports seem to point to driver issues with more that 4 GPUs in one system.  For example, 2 4850x2 work, 2 4850x2 and 1 4850 (5 GPUs) does not work (under various linuxes, hard lock @ X start).

NB:  I have not tried this recently with >4 5800 series GPUs and a 890fx mobo, and 10.4 drivers ... please if someone gets this to work, lets us know!!

 

 

 

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nou
Exemplar

4x HD5970 Support?

it is just games but it works. http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/1.html even with only 1x

i think i seen someone post that more than 4 GPU are working now but it is slow.

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afo
Adept I

4x HD5970 Support?

Thanks a lot for the links.

About that, I have seen in other posts that you need to create an individual context for every GPU and disable crossfire in order to have correct results in the second GPU in HD5970 cards.

Using CLInfo, when I have crossfire enabled, I see one CL_DEVICE_TYPE_CPU and four CL_DEVICE_TYPE_GPU (the correct configuration), but if I disable crossfire in CCC, I see one CL_DEVICE_TYPE_CPU, and only three CL_DEVICE_TYPE_GPU. So, how can I disable crossfire and still have four CL_DEVICE_TYPE_GPU?

My configuration:

WinXP SP3 32 bits

catalyst 10.4

AtiStream 2.1

Visual Studio 2008 SP1

2xHD5970 with MSI crossfire link cable

MSI 790FX-GD70

Phenom II 945

2GB DDR3 1066

No Overclocking, Samples compile fine, I used to work with a HD4350.

I will really apreciate any insight about this

best regards,

Alfonso

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emuller
Journeyman III

4x HD5970 Support?

Originally posted by: afo Thanks a lot for the links.

 

About that, I have seen in other posts that you need to create an individual context for every GPU and disable crossfire in order to havecorrect results in the second GPU in HD5970 cards.

 

Indeed: crossfire must be disabled, 1 context per GPU, *and* generally one thread per context as per docs.

 


Using CLInfo, when I have crossfire enabled, I see one CL_DEVICE_TYPE_CPU and four CL_DEVICE_TYPE_GPU (the correct configuration), but if I disable crossfire in CCC, I see one CL_DEVICE_TYPE_CPU, and only three CL_DEVICE_TYPE_GPU. So, how can I disable crossfire and still have four CL_DEVICE_TYPE_GPU?

 

My configuration:

 

WinXP SP3 32 bits

 

catalyst 10.4

 

AtiStream 2.1

 

Visual Studio 2008 SP1

 

2xHD5970 with MSI crossfire link cable

 

MSI 790FX-GD70

 

Phenom II 945

 

2GB DDR3 1066

 

No Overclocking, Samples compile fine, I used to work with a HD4350.

 

I will really apreciate any insight about this

 

best regards,

 

Alfonso

 

On Linux it is no problem.  On Windows I have no idea, sorry.

 

 

 

 

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