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Intel Chipset Limitation: No Video During Post w/ PCIe x16 slot use?

Last response: in Motherboards
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November 11, 2009 8:59:08 PM

Ok,

So I've been dealing with Asus and a problem: (This is no longer an Asus thread...)

Basically, I've got an Intel based motherboard (G41 Northbridge / ICH7R Southbridge), and the IGM integrated Intel Graphics.

This board has HDMI / DVI / VGA.

The issue is that if I put ANY PCIe card in the x16 PCIe slot, NO DIGITAL VIDEO WILL DISPLAY DURING POST.

(In otherwords, the HDMI and/or DVI ports do not work. In fact, they don't work at all unless you boot to a GUI based OS with the Intel video drivers installed.)

Asus is telling the this is a FLAW in the Intel chipsets, period... and that NO Intel motherboard will display digital video during POST WHEN A PCIe CARD IS INSTALLED IN THE x16 PCIe slot.

In my case, I'm using the Intel based board (a P5QPL-VM EPU) as a home Linux appliance, and needed to multihome the box. So I installed an Intel PCIe NIC in the PCIe x16 slot... (it's a x4 card...)

Had anyone else heard about this [according to Asus] universal failure of all Intel chipsets to support Digital (not VGA) video during POST when using the x16 PCIe card slot with anything by a video card??

Frankly, it seems unbelievable...
a b V Motherboard
November 16, 2009 12:40:44 AM

If I understood you, they say the onboard DVI port is driven by the IGP.
Therefore when you install a discrete video card (which normally disables IGP chips)or other PCI-e card in that slot the DVI which only runs from the IGP doesn't work.
Sorry sounds right or I may have misunderstood.
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November 16, 2009 1:46:45 AM

ahhhh, but the issue here is that you STILL get VGA (analog video) when using the x16 card.

...and of course, the specification for x16 PCIe card slots does include being about to use other cards.

In the borard, you can not use DVI or HDMI, only VGA during POST.
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a b V Motherboard
November 16, 2009 9:21:39 AM

gerhardb said:
(In otherwords, the HDMI and/or DVI ports do not work. In fact, they don't work at all unless you boot to a GUI based OS with the Intel video drivers installed.)

Asus is telling the this is a FLAW in the Intel chipsets, period... and that NO Intel motherboard will display digital video during POST WHEN A PCIe CARD IS INSTALLED IN THE x16 PCIe slot.

That is correct, its an Intel chipset limitation. The G41/43 chipsets are an improvement here, as the previous IGP chipsets such as G33/G31 completely disabled all output from the IGP when inserting any card wider than PCI-E x1 into the native PEG x16 slot. At least with the G41/43, you get one output working via the Intel driver.
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November 19, 2009 4:33:09 PM

Ok.... that's pathetic...

Man...

Of course, I'm more annoyed that Asus does not put a disclaimer on the box indicating that you will not be able to use the PCIe x16 slot for anything if you want digital video.

This does explain why you don't see many boards with anything other than a VGA connector.

GB
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a b V Motherboard
November 19, 2009 8:51:04 PM

The reason is because Intel designed its IGP to support those ADD2 SDVO add-in cards for additional display functionality. The IGP digital output actually gets rerouted to the ADD2 card via some built-in switch in order to provide the display output. So the IGP display controller is literally wired (multiplexed) into the native PCI Express 16 interface located in the Northbridge.

A few boards get around this by not using the native PEG interface in the Northbridge to provide the PCI Express x16 slot. They reroute x4 lanes from the ICH Southbridge in order to provide the PCI Express x16 slot (but this limits all cards installed there to x4 operation). Gigabyte has at least one board that does this.
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December 6, 2009 8:46:47 PM

I'm having the same problem. I need a micro-ATX board with on-board digital video output with resolution up to 1920x1200, and a PCI-express 16x slot.

I've looked around quite exhaustively, and all such boards that I've looked at seem to disable their on-board digital video output ports (DVI-D, HDMI, or the digital portion of DVI-I) if a PCI-e 16x card is inserted. I only found this out after reading the fine print in their manuals.

Are there any boards out there that don't have this limitation?
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December 14, 2009 6:36:04 PM

My issue with this is that it should be clearly printed in large letters on the side of the box:

"PCIe x16 card slot can not be used for any card that is not a video card or larger than PCIe x1 if the intended use of the system includes the on-board DVI / HDMI functionality."

That's pretty straight forward.

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a b V Motherboard
December 14, 2009 9:10:24 PM

This has been the rule for IGP products for...well...as long as there have been IGP and expansion slots on the same motherboard. Previously, it was the AGP slot and IGP that couldn't be used simultaneously.
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April 23, 2010 8:47:49 AM

I'm about to read the replies, but I completely second your statement that "frankly, this seems unbelievable." I have been BURNED by this too!! Absolutely ri-diculous!!! I've spent so much time trying to find workarounds for this problem. Not pleased. :fou: 
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April 23, 2010 8:52:01 AM

Freaking b#$$sh@t. For me, it's the Shuttle SG45H7 that gave me this problem. My bad for not going to Shuttle site, going to the support section, anticipating that their product wouldn't work, going to the FAQ, and finding out that oh hey, this entire computer is severely limited! :)  Have a nice day, sucker!
Sucks...cuz otherwise the PC is perfect for my needs.
Anybody need a really high spec'd Shuttle SG45H7? ;)  (...heh but seriously, if you do, PM me)
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January 14, 2013 9:46:24 PM

Thanks for previous posts.

I put an X4 lane PCIE card into into the X16 PCIE slot and no POST or output to the display. This initially feels like its system down , but on inspection the system does boot and i can get OS access over the ethernet

I have a Gateway SX2802-01 . Chip set here is;

Product Name: WG43M
Description: Intel(R) G45/G43 Express Chipset
String 1: INTEL G43 + ICH10
Reference Designation: Intel(R) G45/G43 Express Chipset.

Very disappointed to find this limitation, went through a BIOS upgrade in the hope of some resolution.

But here it is:
PCI Express* 2.0 Interface • 16 GB/s bandwidth for platform graphics.PCI Express* 2.0

See G45 Data sheet and its clearly documented to only support Graphics cards as its physically hanging off the Graphics memory Hub controller :^(.
.
www.intel.com/Assets/PDF/datasheet/321387.pdf
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