Hi,

For VO.92, the BIOS setup option "Spread Clock Spectrum" could only control the 
external clock generator, it cannot affect PCIe Spread Clock Spectrum. Because 
PCIe Spread Clock Spectrum is a feature controlled by "software strap", which 
is out of the scope of BIOS. 

But for V0.93, in order to pass FCC test, Spread Clock Spectrum of PCIe is 
required to be enabled (by changing the "software strap" bit that I shared 
before), and also the BIOS setup option "Spread Clock Spectrum" is required to 
be hidden from end user. 

 
Thanks,
David  Wei                                 

-----Original Message-----
From: elinux-MinnowBoard [mailto:[email protected]] 
On Behalf Of David Scully
Sent: Saturday, September 10, 2016 3:45 AM
To: [email protected]
Subject: Re: [MinnowBoard] MinnowBoard MAX 0.93 64-Bit & network lost

Thank you for this quick fix so I didn't have to rebuild the 0.93 firmware to
turn this off.

It appears that making this modification has resolved my issues with PCIe
disconnects. I'm still not sure why I didn't see problems with 0.92 with
Spread Clock Spectrum turned on -- Has something changed under the hood for
how that feature works between 0.92 and 0.93?

We're looking at doing some layout review and checking our our eye diagram.
This feature might have pushed our design into a marginal state.



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