6870x2 second GPU freezes under load

BlacKHawK3 · Feb 10, 2014

I have a brand new VisionTek 6870x2 GPU (which is 2 CrossFire-able 6870's stuck on one card). I have not been able to get the second GPU to function in high-performance mode. As long as it stays under 300MHz (both core and memory), or stays in 2D mode it's fine. As soon as it goes to the stock 900MHz core/1050MHz memory, it causes a system freeze.

If I disable the second GPU in Windows and run on the first one, everything works fine. Enabling/disabling Crossfire does not help. I've tried the drivers included from VisionTek, as well as 13.9 and 14.1 beta drivers from AMD. I've tried 3 different PSUs, all of which are working and can run a 6990 or three 7870s - they should handle the 6870x2 easily. GPU-z reports +12V voltages as low as 11.13V on the second GPU (first stays above 11.6V).

Am I missing something on the driver side that would cause this? Does the 6870x2 need a special driver for the onboard CFX or PCI bridge? Or does this thing really need a 1kW PSU? Or is it just a bad GPU on the card?

The rest of my system:
6870x2: http://www.tigerdirect.com/applications/searchtools/item-details.asp?Edpno=853911
ASRock 960GM/U3S3 FX AM3+ AMD 760G uATX motherboard:
Athlon II X2 2.8GHz CPU
500 GB Seagate SATA 6GB/s HDD
8GB GSkill Ripjaws DDR3 1866MHz
600W, 750W, 850W PSUs - these PSUs run much more demanding cards easily, so I really don't think its a PSU issue.

Edit: I also tried reinstalling the OS (Windows 7 Ultimate x64). The only program installed (besides drivers) is Steam.

Kkkk1 · Feb 10, 2014

BlacKHawK3 :

I have a brand new VisionTek 6870x2 GPU (which is 2 CrossFire-able 6870's stuck on one card). I have not been able to get the second GPU to function in high-performance mode. As long as it stays under 300MHz (both core and memory), or stays in 2D mode it's fine. As soon as it goes to the stock 900MHz core/1050MHz memory, it causes a system freeze.

If I disable the second GPU in Windows and run on the first one, everything works fine. Enabling/disabling Crossfire does not help. I've tried the drivers included from VisionTek, as well as 13.9 and 14.1 beta drivers from AMD. I've tried 3 different PSUs, all of which are working and can run a 6990 or three 7870s - they should handle the 6870x2 easily. GPU-z reports +12V voltages as low as 11.13V on the second GPU (first stays above 11.6V).

Am I missing something on the driver side that would cause this? Does the 6870x2 need a special driver for the onboard CFX or PCI bridge? Or does this thing really need a 1kW PSU? Or is it just a bad GPU on the card?

The rest of my system:
6870x2: http://www.tigerdirect.com/applications/searchtools/item-details.asp?Edpno=853911
ASRock 960GM/U3S3 FX AM3+ AMD 760G uATX motherboard:
Athlon II X2 2.8GHz CPU
500 GB Seagate SATA 6GB/s HDD
8GB GSkill Ripjaws DDR3 1866MHz
600W, 750W, 850W PSUs - these PSUs run much more demanding cards easily, so I really don't think its a PSU issue.

Edit: I also tried reinstalling the OS (Windows 7 Ultimate x64). The only program installed (besides drivers) is Steam.

Initially I would have said a PSU problem. However it sounds like a GPU issue. Do you have another PC or freind maybe that you could install it in? Obviously if you get the same issue there it sounds like a bad GPU. You could alwways RMA the card for testing but I know it's a pain.

BlacKHawK3 · Feb 10, 2014

Kkkk1 :

PSU issue was my first impression as well, especially when I saw GPU-z reporting 11.13V on the +12V line at GPU2. However, I can run GPU1 at 900/1050MHz with GPU2 either disabled or pegged below 300/300. I can't run GPU2 above 300/300 even with GPU1 throttled down to reduce power draw.

Also, I know my PSUs are good. I have an OCed 6990 pulling 400+ watts and a tri-7870 rig pulling at least 500 watts, and my PSUs power those through the most demanding of stress tests, 24/7 stable.

I'll try it in a different PC, but unless there is some software issue killing off the second GPU, I'm thinking it's a bad VRM. The power circuits for the two GPUs seem to be independent, each running off one of the twin 8-pin PCIe connectors.

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6870x2 second GPU freezes under load

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