Author Topic: PCIe x16 adjusted to x8.  (Read 831 times)

Offline Traveller

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PCIe x16 adjusted to x8.
« on: Sep 08, 2009, 10:11 PM »
Hi All.

I have just read that in SOME motherbaords which support dual cores, the PCIe speed is automatically reduced to x8 when a dual core cpu is used.

How is it possible to tell which motherboards do this and which don't just by looking at the specifications?

Is there anything else that affects the speed in this way?

I don't understand what it means anyway, but am curious to know what it's all about.

Thanks.

Offline pat

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Re: PCIe x16 adjusted to x8.
« Reply #1 on: Sep 15, 2009, 04:16 PM »
Quote
I have just read that in SOME motherbaords which support dual cores, the PCIe speed is automatically reduced to x8 when a dual core cpu is used.

Dual cores or dual video cards, I have not read anything that indicates the speed of the PCIe bus is affected by a dual core CPU.

Quote
How is it possible to tell which motherboards do this and which don't just by looking at the specifications?

Most will tell this in the manual or list in motherboard specs. As a "general" rule of thumb, when using one video card it will run at the full x16 speed, when SLI or Crossfire is used they will both run at X8 speed. That is only a general rule of thumb, some boards are different, best to read the manual because there is also 3 way video set ups as well.
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Offline Traveller

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Re: PCIe x16 adjusted to x8.
« Reply #2 on: Oct 14, 2009, 07:59 AM »
Hi Pat. That may have been a mistake then. They were probably speaking about graphics cards and not processors.

Thanks.