pcie x8 in an x16 slot - nothing

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View

motherboard: intel dg35ec (http://www.intel.com/support/motherboards /
card: adaptec ASR 2045 (http://www.adaptec.com/en-US/support/raid /

Now from everything I've read, this is supposed to work.  the
motherboards x16 slot is fully wired.  So when I put it in, I get
nothing.  No video, no beeps, nothing.  It's the 2nd adaptec card I've
gotten from them for this issue.

what am I missing?  a moboard setting?

thanks in advance!

Re: pcie x8 in an x16 slot - nothing

Nondisclosure007 wrote:
Quoted text here. Click to load it

The slot pinout is here.


If I had to debug it -

1) Check slot alignment. Any problems fitting the card ? Is the
    card fully seated ?

2) Install a PCI "Port 80" debug card in the PCI slot closest
    to the processor. Start the computer. What codes do you see ?
    Is the only code, an unchanging "00" or "FF" value ? That
    indicates the system isn't coming out of reset. If some
    other code is present, look up the code in the motherboard
    manual (PDF page 68).



If you're getting a code other than "00" or "FF", then it could be
the BIOS is running, has attempted to enumerate the PCI Express
slot and stalled. Then, it could be the BIOS on the Intel motherboard,
doesn't know how to handle non-video cards.

But if the thing is stuck at 00 or FF, it could be a hardware issue.
Such as jamming down "PCIE_RST" or something. Or upsetting "3VSB"
supply rail somehow.


Re: pcie x8 in an x16 slot - nothing

Quoted text here. Click to load it

Thanks Paul.

I figured it out.  As long as I had a monitor plugged into the DVI
port, then the slot wouldn't work.  However, how I hooked up a monitor
to the VGA port and viola, it worked.

Re: pcie x8 in an x16 slot - nothing

Nondisclosure007 wrote:
Quoted text here. Click to load it

I think I can see why this happened. Kinda scary if true, in terms
of the cluelessness on Intel's part.

There is mention in the Intel user manual e35350001us of the
"Add2/MEC" option on the G35. Look at the block diagram on
PDF page 14. A DVI transmitter is tied to "something" on the


Some background on SDVO for Add2/MEC here.


This is the G35 datasheet. See PDF page 293, for how two SDVO outputs
share pins with the PCI Express. It could be, that the "DVI transmitter"
mentioned on page 14 of the user manual, is actually wired to the PCI
Express x16 slot. And that could be the source of interference. Plug
in the DVI, turns on the DVI transmitter, and the G35 responds thinking
it is driving an Add2/MEC card. That disables the PCI Express mode of
operation, and runs the slot so it can drive two SDVO devices. Effectively,
one SDVO device is hardwired to your motherboard.


In effect, it is as if this thing is soldered in parallel to
your PCI Express slot. This is an Add2 card for DVI output. They
may have placed that chip and DVI connector, on your motherboard
instead. If it was a removable card, then by unplugging this,
you would have had unrestricted usage of your PCI Express slot.
It still would not have solved the problem, of not being able
to drive a DVI monitor at the same time as you use the PCI
Express slot.


I would never have guessed such a thing, but that is as close as
I can get to explaining it for you. How did you even think of
trying VGA ? With so many DVI-only LCD monitors out there, there
aren't a lot of options to change to VGA when you want to.


Re: pcie x8 in an x16 slot - nothing

Quoted text here. Click to load it

Funny you should ask, I think I got the idea from you.

http://groups.google.com/group/alt.comp.hardware/browse_thread/thread/20dee =

hopefully the link will take to an article I posted quite a while
ago.  And I think it was you that lead me down that path.

Site Timeline