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dravisher
Journeyman III

Does PCIe 3.0 with the HD 7950 work on Linux?

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Hi. My hardware is:

Alienware Aurora R4, which consists of:

Intel Core i7-3930K

Intel X79-based motherboard

I'm running openSUSE 12.2 with Catalyst 12.8 (driver 8.982) and AMD APP SDK 2.7. In Catalyst the bus is stated to be PCI Express 2.0 x16, but AFAIK all of the hardware should be able to support PCIe 3.0. When I run the BufferBandwidth sample that comes with AMD APP SDK as "BufferBandwidth -pcie" I get a bandwidth of ~6-7 GB/s, which is consistent with PCIe 2.0 x16.

Is it possible to get PCIe 3.0 mode working in Linux with this hardware combination?

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hsaigol
Adept III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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I have the following systems and Gen 3 works, trust me on this one.
My systems
Intel x79TO & intel x79SO motherboard & ASUS Z77 motherboards --> All three have Gen3 working
Intel i7 3930k processor

The default SBIOS that comes with the x79 motherboards did not support gen3, but as soon as i updated from intels website Gen3 speed was available

My job depends on me testing in Gen3 (in linux), lets just say that so i know for a fact it works

As you are using an alienware branded PC i'm guessing you'll have to check dells website with your system service tag under support and downloads and check if they have a newer SBIOS.
Otherwise bug them for support.

Also why would you explicitly say this is a linux issue, i am confident you would see the same thing in windows

View solution in original post

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rocky67
Journeyman III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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I need to understand if the PCI Express in the catalyst hardware can be used in 2.0 x 16 AFAIK options. This will enable me to make use of appropriate applications.

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yurtesen
Miniboss

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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Your processor is too old. AFAIK you need a 3rd generation Intel processor.. It appears you have to upgrade.

http://ark.intel.com/products/63697/Intel-Core-i7-3930K-Processor-%2812M-Cache-up-to-3_80-GHz%29

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dravisher
Journeyman III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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I have essentially the same hardware at home (i7-3930K, Asus P9X79 Deluxe motherboard, AMD HD 7970 GPU) running Windows 7 and PCIe 3 works fine there (I get ~11-12 GB/s as measured by BufferBandwidth -pcie). As I recall Intel's Sandy Bridge-E (like the i7-3930K) were made to support PCIe 3, but since there were no PCIe 3 capable cards available at the time they weren't actually specified for it officially.

See for example http://www.anandtech.com/show/5264/sandy-bridge-e-x79-pcie-30-it-works

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yurtesen
Miniboss

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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Yes, it appears I was not totally correct. But if the support is unofficial, then it depends on the motherboard manufacturer if they decide to support it or not, and with bios version. You should maybe check your bios to see if there is an option to enable PCIe 3.0 perhaps?

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dravisher
Journeyman III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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Indeed it may well be an issue with the motherboard, and unfortunately there is no mention of it in the BIOS. At some point I will probably try either installing Windows on the Alienware or Linux on my home computer. But I'd still be interested to hear if anyone has actually gotten PCIe 3 to work with AMD cards under Linux, and if so on what hardware.

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hsaigol
Adept III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

Jump to solution

I have the following systems and Gen 3 works, trust me on this one.
My systems
Intel x79TO & intel x79SO motherboard & ASUS Z77 motherboards --> All three have Gen3 working
Intel i7 3930k processor

The default SBIOS that comes with the x79 motherboards did not support gen3, but as soon as i updated from intels website Gen3 speed was available

My job depends on me testing in Gen3 (in linux), lets just say that so i know for a fact it works

As you are using an alienware branded PC i'm guessing you'll have to check dells website with your system service tag under support and downloads and check if they have a newer SBIOS.
Otherwise bug them for support.

Also why would you explicitly say this is a linux issue, i am confident you would see the same thing in windows

View solution in original post

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dravisher
Journeyman III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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Thanks. I framed it as a Linux issue because I could find no information about whether or not PCIe 3 worked with AMD cards at all under Linux, so thanks for responding :-). It seems likely that it is a BIOS issue with my specific machine then.

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hsaigol
Adept III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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i checked the bandwidth using 'BufferBandwidth -pcie' on the x79 system and i got ~11GB/s read and write so that it looks to be working correctly

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dravisher
Journeyman III

Re: Does PCIe 3.0 with the HD 7950 work on Linux?

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For completeness I'll mention that I have installed the newest BIOS (currently A05), which enabled PCIe 3.0 in both Windows and Linux for me, even though the BIOS release notes only made a vague reference to some PCIe changes.

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