Understanding of chipset PCI-Express lanes

The B150 chipset has 8 PCI-e lanes available from the platform controller hub, but there are 16 more lanes available from the CPU.

_{From http://www.intel.co.uk/content/www/uk/en/chipsets/business-chipsets/b150-chipset.html}

Your graphics card would normally be plugged into the first x16 port that comes off the CPU, further devices would come off the ports that remain on the PCH (the B150 controller).

Ethernet, audio, M.2 SSDs and other devices built into the motherboard might take up those remaining 8 ports, but as your graphics card is on the x16 slot from the CPU you won't really care too much and should be fine to use a 970 with this motherboard.

As an example the ASUS B150 Pro motherboard manual shows

Expansion slots
- 1 x PCI Express 3.0/2.0 x16 slot (@ x16 mode)
- 1 x PCI Express 3.0/2.0 x16 slot (max @ x4 mode)
- 2 x PCI Express 3.0/2.0 x1 slots

If you only had 8 lanes available then that first slot wouldn't be listed as being "@ x16 mode".

Mokubai

Posted 2016-12-18T18:31:58.213

Reputation: 64 434

And what about CPU integrated video? Does it use any lanes? – Xeniya L – 2016-12-18T19:03:07.580

CPU integrated video is normally disabled once a dedicated card is installed. I'm not convinced this is the case as I am a new i7-6700 owner and have a dedicated card and can still see the Intel video in device manager. The graphics card is definitely at x16, so it is possible that the integrated graphics is on a different internal bus on the CPU. I'll have a look. – Mokubai – 2016-12-18T19:08:06.557

but I'm going to use the integrated video for Linux host system, and assign GTX 970 card to guest virtual machine with Windows and use them simulateniously. Will it be possible? – Xeniya L – 2016-12-18T19:15:08.700

@XeniyaL That is another question entirely. "It depends" is all I can really say. Some people say yes, some say maybe, and some say no. It sounds like it depends on your motherboard, and it's difficult to find out if it will work out beforehand: https://communities.intel.com/thread/87011 http://www.tomshardware.co.uk/answers/id-3191672/intel-graphics-gpu-time.html http://askubuntu.com/questions/732713/is-it-possible-to-use-dedicated-gpu-and-integrated-gpu-at-the-same-time-if-so-h

– Mokubai – 2016-12-18T19:25:39.573

And what if buy MB with z170 chipset which has 20 lines? Will it be enough for 970 card to be used in parallel with the integrated video? – Xeniya L – 2016-12-18T19:34:51.953

Honestly I do not know. It might be worth asking a new question and being clear about what your requirements and what the problem you are trying to solve is. I've only ever needed a single dedicated card and not cared enough about the integrated graphics to bother with it. I know several years ago this was highly dependent on your motherboard being able to leave the integrated graphics enabled, but don't know if that is still the case. Otherwise the site search might show up something for you... – Mokubai – 2016-12-18T19:38:30.350

1You have 16 lanes coming from your CPU, then a further 8 lanes from the motherboard PCH for other devices such as USB3, Audio, ethernet and so on. – Mokubai – 2016-12-18T18:39:34.190

That's good. Thank you. Are you sure? Where can I read about this? – Xeniya L – 2016-12-18T18:42:56.363

I've posted an answer with a link to the Intel page for the B150, but the main place to look at will be your motherboard manual. – Mokubai – 2016-12-18T18:57:11.123

Understanding of chipset PCI-Express lanes

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