Re: [gentoo-user] strange problem (no video output) on new PC

[Mick]

On Thursday, 11 July 2019 23:31:51 BST Jack wrote:
> I'm hoping the cumulative wisdom of the assembled masses might be able
> to figure out what I'm clearly missing, assuming there IS something I'm
> missing.
>
> I've recently assembled a new PC, with an MSI B350-Tomahawk motherboard
> and a Ryzen 5 2600 CPU.  (We'll skip that I ended up actually buying an
> older Ryzen just to upgrade the BIOS.)  The problem is that I have now
> tried three different PCI-E graphics cards, and have gotten no video
> signal from any of them.  I do get a video signal from an ancient PCI
> graphics card.  One of the cards is a very old Radeon, one is a
> slightly less old nVidia, and the newest is (from lspci) "Advanced
> Micro Devices, Inc. [AMD/ATI] Cape Verde XT [Radeon HD 7770/8760 / R7
> 250X]."
>
> What I find particularly odd is that if I log in blind, and then issue
> startx, X (startkde) seems to be running fine.  I ssh in from another
> PC, and the X log shows the Radeon driver loading, the monitor being
> recognized on the appropriate connector, the EDID received, and the
> right resolution being chosen.  (Even without all the AMD drivers and
> firmware loaded, at least it also seemed to start with the VESA driver,
> but still no output signal.)
>
> I can easily believe the old radeon card is dead, and possibly even the
> nVidia card.  However, given what I see in the logs with the new radeon
> card, I find it hard to believe the card is actually defective.  (Just
> purchased used on eBay, so I do have to admit the possibilty.)
> However, I have trouble imagining what else could be the problem.  I've
> tried two different cables (both of which work fine for the PCI card)
> but both use DVI to VGA adaptors, although I can't imagine why that
> would matter now, if they worked for a different card.  I have ordered
> a new DVI cable to go directly from the card to the monitor, so
> hopefully I'll get that and be able to test it within a few days.
>
> Can anyone else thing of what the problem might be, and if there is any
> troubleshooting I could try?
>
> Jack

Brief response for now:

If dmesg after you login remotely shows the graphics card firmware is 
available in the kernel, radeon/nvidia drivers are loading and no errors are 
printed, then hardware wise your PC ought to be OK.

If /var/log/Xorg.0.log shows no errors with drivers and monitor, then I don't 
know what to suggest other than following a process of elimination, by trying:

- different cables
- different monitor

However, if cables or monitor were at fault I would expect warnings to show up 
in the log files.
-- 
Regards,

Mick