topic Re: 3rd Gen Intel Core bifurcation in Mobile and Desktop Processors

3rd Gen Intel Core bifurcation

gabiz_ro — Tue, 16 Apr 2024 11:22:49 GMT

I try to split CPU PCIe lanes from x16 to 2 x8 or 1 x8 2 x4 but without luck.

All I get is PCIe port downgraded to x8.

System in case is HP 8300 with Intel I7 3770 and Q77 chipset.

From little info found on internet there is no clear answer if Q77 support such thing as CPU PCIe lanes splitting .

Although is not clear why PCH chipset depends on CPU PCIe lines if are in x16 or other mode.

So question, how chipset affect CPU PCIe splitting lanes?

Does indeed Q77 disable this?

Re: 3rd Gen Intel Core bifurcation

n_scott_pearson — Tue, 16 Apr 2024 18:00:54 GMT

First off, this is a long discontinued product, so you aren't going to get any help from Intel. It will take community support to answer it.
I do not believe that the chipset has anything to do with the implementation of bifurcation of the CPU's PCIe lanes. I believe that this is exclusively the domain of the processor and its programming by the BIOS. I believe that your problem is poor bifurcation support in your motherboard's BIOS.
That said, I am no expert in this part of the BIOS. I have sent a query to a couple of former (retired) Intel Desktop Board BIOS engineers. We'll see what they have to say (though it may take a couple of days to get a response).
...S

Re: 3rd Gen Intel Core bifurcation

gabiz_ro — Wed, 17 Apr 2024 08:09:14 GMT

Thanks

Waiting your answer.

In the meantime looking for differences of 77 chipset from little info I could find Z77 say it support 1x16 or 2x8 or 1x8 2x4 but for Q77 "not specified" or 1x16

Too bad Intel doesn't specify this in any document.

Re: 3rd Gen Intel Core bifurcation

gabiz_ro — Wed, 17 Apr 2024 11:15:10 GMT

Still looking for info I get this from some datasheet
PCI Express x16 from processors can be one PCI Express x16 or two
PCI Express x8 or One PCI Express x8 + Two PCI Express x4 by jumper setting with
C216 chipset. It only supports one PCI Express x16 with Q77 chipset

So it looks like I'm out of luck.