Is there a dedicated PCIe lanes in CPU for GPU after the advertised PCIe lanes on CPU?

[NJohn5]

I have been hearing this myth for long time. Some people claims that Intel CPU have dedicated PCIe Lanes for GPU excluding the advertised PCIe Lanes. For eg, A i7-7800X cpu have 28 lanes. But it says there is 16x dedicated lane for GPU excluding this 28Lanes. Which means, CPU have 28+16 lanes in total. But most people believe that GPU use the PCIe lanes advertised by Intel on the CPU spec. I want to know if there is any truth in this mythical PCIe lane for GPU. Thank you.

[idata · Accepted solution]

Hello NikzJon,

Thank you for joining the Processors Community. I can sure help with your inquiry.

Based in the processor's datasheet the only specification for the lanes is referred to the PCI Express for general purpose, there is no mentioned about GPU dedicated lanes, so it's 28 PCI Express lanes max. Once you install a graphics card via PCI Express it will be connected through the 28 lanes, and how many does the graphics card take will depend on the card manufacturer. I am afraid that I have no heard about this myth and the information from our end does not confirm it.

Hope this information helps.

Regards,

Amy C.

[NJohn5]

Thank you for the clarificatio.

[NJohn5]

Btw for myself, this doubt arised for me when I thought about i7-7700K and i7-7800X. First one have a integrated graphics and later have none. So does the Integrated Intel HD Graphic processor also use the same advertised PCIe lanes in i7-7700K?

[idata]

For this processor the scenario changes, the 16 PCI Express lanes supported for this model does not related to the internal graphics controller. Remember that the 16 lanes are for plug and play devices(video cards, sound cards etc) connected physically through PCI Express. For the integrated graphics controller there is a whole different section in the processor which is not PCI Express related.

If you have more questions, please let us know.

Regards,

Amy C.

[n_scott_pearson]

Let me say this in a more understandable way...

First of all, the so-called "dedicated PCIe lanes for graphics" are indeed included in the PCIe lane count. If ark.intel.com says there are 28 PCIe lanes, then there are 28 PCIe lanes, period.

Secondly, these PCIe lanes are dedicated to external graphics only when an external graphics card is present. If no card is present, then these lanes are used to support whatever device(s) is/are instead plugged into the associated PCIe connector(s).

Hope this helps,

...s

[NJohn5]

I guess this solves this topic. Thank you.