Are Video Cards smart?


A

athiker

I use a notebook and an external monitor on a HP (dv7-6b78us). The
monitor is fed by a HDMI cable.

The system is set so that if the external monior is receiving a signal
the notebook screen is black.

If I turn off the external monitor while the system is running does
the video card somehow realize this and quit sending a signal? Like
turn itself off or something?

How about if I set the screen saver to blank?

Thanks for any answers.
 
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Y

Yousuf Khan

I use a notebook and an external monitor on a HP (dv7-6b78us). The
monitor is fed by a HDMI cable.

The system is set so that if the external monior is receiving a signal
the notebook screen is black.

If I turn off the external monitor while the system is running does
the video card somehow realize this and quit sending a signal? Like
turn itself off or something?
No, I doubt this will cause anything to happen. The reason the computer
can detect whether to send signals to the external or internal monitor
is depending on whether the laptop's lid is open or closed, and also
whether it sees a signal coming from the external HDMI (or DVI, or VGA)
port. Turning the external monitor off will simply result in there being
no signal being sent to either monitor.

Yousuf Khan
 
A

athiker

No, I doubt this will cause anything to happen. The reason the computer
can detect whether to send signals to the external or internal monitor
is depending on whether the laptop's lid is open or closed, and also
whether it sees a signal coming from the external HDMI (or DVI, or VGA)
port. Turning the external monitor off will simply result in there being
no signal being sent to either monitor.

Yousuf Khan

Thanks. FWIW, the system is set so that closing the lid does nothing.

If that matters.
 
S

SC Tom

Jason said:
Closing the lid may not cause the computer to react, but it'll get plenty
hot...
Not mine. I use that all the time to move my laptop from room-to-room. It's
easier to carry with it closed than open, and sometimes I'll set it on the
table closed and leave it that way for a while. I feel no additional heat
upon raising the lid, and my temp monitors don't don't show any increase in
CPU or GPU temps.

I guess if a laptop draws or pushes air through the keyboard, or has air
ports on that surface, it would heat up, but I can't recall ever using any
that did that.
 
Y

Yousuf Khan

Thanks. FWIW, the system is set so that closing the lid does nothing.

If that matters.
I don't think it matters. Even if you set it to do nothing, the internal
display is still turned off.

Yousuf Khan
 
P

Paul

I use a notebook and an external monitor on a HP (dv7-6b78us). The
monitor is fed by a HDMI cable.

The system is set so that if the external monior is receiving a signal
the notebook screen is black.

If I turn off the external monitor while the system is running does
the video card somehow realize this and quit sending a signal? Like
turn itself off or something?

How about if I set the screen saver to blank?

Thanks for any answers.
Well, look at the pinout of HDMI, and figure it out.

http://en.wikipedia.org/wiki/Hdmi

The video card can tell when an HDMI monitor is connected to the HDMI connector.
One way, is impedance sensing. Impedance sensing in video cards has been
available, on VGA, DVI, HDMI, for a number of years now.

Video_card --------------------> resistive termination in external monitor
TMDS Diff Pairs 100 ohms across each diff pair

So the video card does know, when a monitor is cabled up, to the port.
It can "feel" the 100 ohm load, on each TMDS pair.

This doesn't say anything about the power state though. The communications
are unidirectional on those wires. The video card can't tell whether the
external monitor is powered or not.

(Pin 18 carries +5V to the monitor, such that the SDA/SCL is always operational,
even when the monitor is switched off. Again, the video card can't tell whether
the monitor is using current from this pin or not. If the monitor always drew
current from the pin, then you'd have no state change to detect.)

The "CEC" signal is the only one that is vaguely interesting. CEC was invented
for the sole purpose, of having a communications channel between HDMI devices.

"The CEC allows HDMI devices to control each other when necessary
and allows the user to operate multiple devices with one remote
control handset."

That is used in home theater applications (for autonomous equipment
connected via HDMI). It allows equipment state to be communicated,
such that clicking a remote, turns off all the gear at once.

Someone asks the question here, whether Windows looks for CEC, and the
answer isn't very encouraging for direct hardware support. Apparently
one company sells an adapter, to convert between USB and CEC, as a means
to complete the hardware path (http://www.rcaware.com/). But whether
that supports all possible, bidirectional communications, isn't clear.
If I had to guess, what they could be doing, is converting from CEC
messages, to IR Blaster protocol on USB.

http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/does-ms-have-any-intentions-to-support-hdmi-cec-in/aeecfe1d-7889-4826-80cb-8ae0a39d67d4

For that to even have a chance of working, the sequence would go like this.

1) Push soft power button on external HDMI monitor.
2) HDMI monitor sends packet over CEC, to computer.
3) HDMI monitor then powers down.
4) Now, it's up to the computer, to decide what to do with
the CEC message it got. Do you want the computer to shut
down, when CEC says to shut off ? Etc. If CEC didn't work
directly, then you'd try the rcaware.com product, and if
the computer was running Media Center, maybe, something would
happen.

I wouldn't expect your average LCD computer monitor, to be
using CEC that way. Maybe a large screen TV set would send stuff
down CEC, but exactly what and when, I can't predict. In a
home theater application, you would hope pressing the power
button on your 60" LCD TV, would turn off the connected
DVR at the same time. And the CEC signal on the HDMI cable,
would be a potential path for such a communications to follow.

*******

It should only take you a couple minutes, to test this on your
laptop plus HDMI based external monitor. Switch off the HDMI
monitor, notice the laptop screen does not light up, the laptop
continues to run. Now, switch on the HDMI monitor, and notice
that nothing has changed, and the session is still running.

If you wanted something more than that, it might take the rcaware.com
device, but even then, if the HDMI monitor doesn't send a packet
on CEC at power down, then there's nothing for the adapter to
work with. So it's very iffy, with regard to getting it to work.
It's more likely to work, with the 60" LCD TV, clicking the
power button on the remote, and that would be able to
trigger a chain of events.

If I was a betting man, I wouldn't make much money betting
a person would get this working.

If you unplug the HDMI cable, *then* the laptop should
re-light the main screen. The impedance sensing generates
"events", if a cable is unplugged, or plugged in.

HTH,
Paul
 
G

Gene E. Bloch

I use a notebook and an external monitor on a HP (dv7-6b78us). The
monitor is fed by a HDMI cable.

The system is set so that if the external monior is receiving a signal
the notebook screen is black.

If I turn off the external monitor while the system is running does
the video card somehow realize this and quit sending a signal? Like
turn itself off or something?

How about if I set the screen saver to blank?

Thanks for any answers.
If you had turned the monitor off yourself, you would have learned the
answer in just seconds.

That is a good idea for another reason. It is possible that not all
computers will react the same way, so any answer[1] I gave you might be
wrong for you.

[1] Which I would have obtained by ... trying it.
 
C

charlie

I use a notebook and an external monitor on a HP (dv7-6b78us). The
monitor is fed by a HDMI cable.

The system is set so that if the external monior is receiving a signal
the notebook screen is black.

If I turn off the external monitor while the system is running does
the video card somehow realize this and quit sending a signal? Like
turn itself off or something?

How about if I set the screen saver to blank?

Thanks for any answers.
If you had turned the monitor off yourself, you would have learned the
answer in just seconds.

That is a good idea for another reason. It is possible that not all
computers will react the same way, so any answer[1] I gave you might be
wrong for you.

[1] Which I would have obtained by ... trying it.
Within the general subject - -
The newer videocards with on board sound can detect a monitors sound
circuitry. It would be possible for the video card to determine such
things as the native video resolution of the monitor, and so forth.
What a given card does or does not do is up for grabs, since mfrs rarely
bother to say.
 
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P

Paul

charlie said:
I use a notebook and an external monitor on a HP (dv7-6b78us). The
monitor is fed by a HDMI cable.

The system is set so that if the external monior is receiving a signal
the notebook screen is black.

If I turn off the external monitor while the system is running does
the video card somehow realize this and quit sending a signal? Like
turn itself off or something?

How about if I set the screen saver to blank?

Thanks for any answers.
If you had turned the monitor off yourself, you would have learned the
answer in just seconds.

That is a good idea for another reason. It is possible that not all
computers will react the same way, so any answer[1] I gave you might be
wrong for you.

[1] Which I would have obtained by ... trying it.
Within the general subject - -
The newer videocards with on board sound can detect a monitors sound
circuitry. It would be possible for the video card to determine such
things as the native video resolution of the monitor, and so forth.
What a given card does or does not do is up for grabs, since mfrs rarely
bother to say.
Video card sound options, are digital ones, and they travel over HDMI or DVI.
The user can select to direct sound, to the HDMI cable if they want. Then,
any speakers in the monitor can be used. The video card drivers in that case,
would include a sound driver, and then there would be an entry for that as
a sound output option, in the appropriate Windows control panel.

The monitor resolution support is contained in the EDID chip inside
the monitor, and that is read out via SDA/SCL serial interface. That's
what is supposed to make the monitor Plug And Play. Why some monitors
show up as Generic in Windows, is beyond me. You'd think if the EDID was
corrupt or substandard, there'd be an error dialog on the screen about it.
You can use the entechtaiwan moninfo utility, to examine EDID. It has
the ability to scan in real time, while the hardware is running.

There is this on the HDMI cable, but I haven't read anything about
support for this in Windows (or other OSes for that matter). You can
be sure, there is a logic block in your GPU that sees the signal. And
all that is needed, is software to use it. Hardware guys never miss
an opportunity like that.

http://en.wikipedia.org/wiki/Consumer_Electronics_Control#CEC

"It is a one-wire bidirectional serial bus that is based on the
CENELEC standard AV.link protocol to perform remote control functions.
CEC wiring is mandatory, although implementation of CEC in a product
is optional."

"The following is a list of HDMI-CEC commands:

[ The following edited, to fit on the screen... ]

* One Touch Play - switch TV on when playback starts
* System Standby - switch multiple devices to standby mode
* Preset Transfer - transfers the tuner channel setup to another TV set
* One Touch Record - record HDTV screen source, on selected recording device
* Timer Programming - electronic program guide (EPGs) related functions
* System Information - checks components for bus address / configuration
* Deck Control - play, pause, rewind, of a playback component
* Tuner Control - control the tuner of another component
* OSD Display uses the OSD of the TV set to display text
* Device Menu Control - Passthru to another device menu system
* Routing Control - controls the switching of signal sources
* Remote Control Pass Through - (one remote to control everything)
* Device OSD Name Transfer - transfers preferred device names to the TV set
* System Audio Control - volume control for an AV receiver,
"

Nothing there really applies to the computer to LCD monitor case that
closely (the message set wasn't defined with computers in mind).
System Standby might be useful, like putting your HTPC to sleep,
when you turn off the connected HDMI TV set. But those message functions
don't have a strong computer component to them. The messages listed
there, seem to be for AV components in the TV room.

While they list an Ethernet option for HDMI 1.4, that would be a stretch
for inclusion in a GPU. But the GPU designer could just buy an IP block
and stuff that in the GPU. And both NVidia and AMD have their own Ethernet
blocks anyway (as both have made chipsets). It wouldn't be hard to include
one, and mainly a pain to write driver software for it (i.e. figuring out
when to enable it, and have IP routing to it). You would need something
like Media Center software to integrate with that somehow, and I'm sure
the Media Center staff have better things to do (like make tuner cards
and set top boxes work first).

http://en.wikipedia.org/wiki/HDMI

As for the original premise of this thread, the subject line,
video cards are undoubtedly "smart", in that they can do a form
of general purpose computing. And they have all sorts of facilities
at their disposal. But without software to run all that stuff, much
of that could remain dormant.

We already have examples of that dormancy, on TV tuner cards, where
functions the hardware guys put in the tuner, there's no software to
run them. Even product advertising, can make claims about the
included hardware, and then they never write software to make it work.
It's not like every spigot on the hardware you buy, had software for it.

Paul
 
P

Paul

Gene said:
As I understand it, DVI does *not* support sound...
This is the first reference I found in a search.
Maybe not very convincing.

http://www.digitalhome.ca/forum/showthread.php?t=75963

There's a ref to it here as well.

http://en.wikipedia.org/wiki/Hdmi

"DVI connectors on PC video cards have also been
increasingly able to take advantage of HDMI features
such as audio output."

http://en.wikipedia.org/wiki/Dvi

"To promote interoperability between DVI and HDMI devices,
HDMI source components and displays support DVI signalling.
An HDMI display can be driven by a single-link DVI-D source,
since HDMI and DVI-D define an overlapping minimum set of
supported resolutions and frame buffer formats.

In the reverse scenario, a DVI monitor that lacks optional
support for HDCP might be unable to display protected content,
even though it is otherwise compatible with the HDMI source.

Features specific to HDMI, such as remote-control,
audio transport, xvYCC, and deep-color, are not usable in
devices that only support DVI signalling. However, many devices
can output HDMI over a DVI output (examples: ATI 3000-series
and NVIDIA GTX 200-series video cards),[7] and some multimedia
displays accept HDMI (including audio) over a DVI input.
Exact capabilities vary from product to product."

This answer isn't nearly as helpful. But at least it
does highlight some things that aren't likely to work
over DVI. The color space thing, and missing CEC signal pin.

http://www.hdmi.org/learningcenter/faq.aspx#83

"What is the difference between DVI and HDMI?

HDMI is DVI with the addition of:

* Audio (up to 8-channels uncompressed)
* Smaller Connector
* Support for YUV Color Space
* CEC (Consumer Electronics Control)
* CEA-861B InfoFrames

So you might hear audio, or you might be imagining things :)

Paul
 
G

Gene E. Bloch

http://www.hdmi.org/learningcenter/faq.aspx#83

"What is the difference between DVI and HDMI?

HDMI is DVI with the addition of:

* Audio (up to 8-channels uncompressed)
* Smaller Connector
* Support for YUV Color Space
* CEC (Consumer Electronics Control)
* CEA-861B InfoFrames

So you might hear audio, or you might be imagining things :)
The above, from the end of your post, says
" HDMI is DVI with the addition of:
* Audio (up to 8-channels uncompressed)"

Which implies to me that DVI lacks audio or audio wouldn't need to be
added.

This site,

https://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&dlc=en&docname=c00508387

(AKA http://tinyurl.com/cs5fblb)
says
"For DVI output to HDMI input, you must use a DVI-to-HDMI adapter cable
and an audio cable."

Both agree with my previous experiments with DVI to DVI and with DVI to
HDMI.

I can't repeat them here at this time because this monitor lacks audio.
 
C

charlie

I can't repeat them here at this time because this monitor lacks audio.
While you were typing this, I was fighting a reoccurring problem with
sound and an LCD Display with built in HDMI sound.

The problem is that this P/C uses AMD HD video card(s) that have HDMI
sound, and connect with the appropriate cable to the display.
Every time AMD issues a driver revision that addresses various video
problems in popular games, it seems they have ignored sound related
problems that can occur during the install process.

Video card sound system
Mother board sound system (Realtec 1600 chip (A variant on some Asus MBDs)

Windows "generic" sound drivers that are compatable with the MBD sound
hardware.
Realtec specific drivers for the MBD sound hardware
AMD Video card sound drivers.

Usual result after updating video drivers --
MBD sound active, Video Card sound not active
Temporary fix that may or may not survive a reboot (with this video
driver rev., it's currently not surviving the re boot!
Use Device "mangler" to disable both the MBD sound and the video card
sound, then re-enable the video card sound.
When you uninstall the Realtec sound drivers, the generic Microsoft
windows drivers may activate and take over, using the MBD sound system.
Obviously, this kills the Display HDMI sound, since the Realtec sound
outputs are back panel, with no way to get them to the display.
GRR!
 
P

Paul

Gene said:
The above, from the end of your post, says
" HDMI is DVI with the addition of:
* Audio (up to 8-channels uncompressed)"

Which implies to me that DVI lacks audio or audio wouldn't need to be
added.

This site,

https://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&dlc=en&docname=c00508387

(AKA http://tinyurl.com/cs5fblb)
says
"For DVI output to HDMI input, you must use a DVI-to-HDMI adapter cable
and an audio cable."

Both agree with my previous experiments with DVI to DVI and with DVI to
HDMI.

I can't repeat them here at this time because this monitor lacks audio.
Well, so far, I'm not seeing any reference to "standards", to
see how this is possible. (That people experience audio, when
using a DVI cable from their computer to TV.)

I expect it's the result of both ends of the link, actually
having HDMI capable logic blocks. And then the "subset" support
is no longer an issue.

Then, it's up to the EDID on the monitor (somehow), to tell the
computer, what to send. Since CEC is missing on a DVI connector,
it's not likely the two ends could communicate bidirectionally with
one another. That leaves some information in EDID over DDC
as a possible solution (how monitor tells computer it has speakers).

http://en.wikipedia.org/wiki/Extended_display_identification_data

"EIA/CEA-861 extension block

The CEA EDID Timing Extension... adding Short Video Descriptors
and advanced audio capability/configuration information... "

So that could be, how the video card finds out the display device
has potential audio channels, and sends the audio. And it sends
the audio, because the monitor told it to. Effectively bypassing
the subset issue (i.e. monitor is indicating it's not limited
to the base subset of features).

There are already a number of historical notes on this standard,
so what's one more for consumers to deal with ? (Like
figuring out where to get the S/PDIF audio signal, to plug into
the top of your Nvidia video card.) There have been a few
bumps along the road already.

Paul
 
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A

athiker

Well, look at the pinout of HDMI, and figure it out.

http://en.wikipedia.org/wiki/Hdmi

The video card can tell when an HDMI monitor is connected to the HDMI connector.
One way, is impedance sensing. Impedance sensing in video cards has been
available, on VGA, DVI, HDMI, for a number of years now.

Video_card --------------------> resistive termination in external monitor
TMDS Diff Pairs 100 ohms across each diff pair

So the video card does know, when a monitor is cabled up, to the port.
It can "feel" the 100 ohm load, on each TMDS pair.

This doesn't say anything about the power state though. The communications
are unidirectional on those wires. The video card can't tell whether the
external monitor is powered or not.

(Pin 18 carries +5V to the monitor, such that the SDA/SCL is always operational,
even when the monitor is switched off. Again, the video card can't tell whether
the monitor is using current from this pin or not. If the monitor always drew
current from the pin, then you'd have no state change to detect.)

The "CEC" signal is the only one that is vaguely interesting. CEC was invented
for the sole purpose, of having a communications channel between HDMI devices.

"The CEC allows HDMI devices to control each other when necessary
and allows the user to operate multiple devices with one remote
control handset."

That is used in home theater applications (for autonomous equipment
connected via HDMI). It allows equipment state to be communicated,
such that clicking a remote, turns off all the gear at once.

Someone asks the question here, whether Windows looks for CEC, and the
answer isn't very encouraging for direct hardware support. Apparently
one company sells an adapter, to convert between USB and CEC, as a means
to complete the hardware path (http://www.rcaware.com/). But whether
that supports all possible, bidirectional communications, isn't clear.
If I had to guess, what they could be doing, is converting from CEC
messages, to IR Blaster protocol on USB.

http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/does-ms-have-any-intentions-to-support-hdmi-cec-in/aeecfe1d-7889-4826-80cb-8ae0a39d67d4

For that to even have a chance of working, the sequence would go like this.

1) Push soft power button on external HDMI monitor.
2) HDMI monitor sends packet over CEC, to computer.
3) HDMI monitor then powers down.
4) Now, it's up to the computer, to decide what to do with
the CEC message it got. Do you want the computer to shut
down, when CEC says to shut off ? Etc. If CEC didn't work
directly, then you'd try the rcaware.com product, and if
the computer was running Media Center, maybe, something would
happen.

I wouldn't expect your average LCD computer monitor, to be
using CEC that way. Maybe a large screen TV set would send stuff
down CEC, but exactly what and when, I can't predict. In a
home theater application, you would hope pressing the power
button on your 60" LCD TV, would turn off the connected
DVR at the same time. And the CEC signal on the HDMI cable,
would be a potential path for such a communications to follow.

*******

It should only take you a couple minutes, to test this on your
laptop plus HDMI based external monitor. Switch off the HDMI
monitor, notice the laptop screen does not light up, the laptop
continues to run. Now, switch on the HDMI monitor, and notice
that nothing has changed, and the session is still running.

If you wanted something more than that, it might take the rcaware.com
device, but even then, if the HDMI monitor doesn't send a packet
on CEC at power down, then there's nothing for the adapter to
work with. So it's very iffy, with regard to getting it to work.
It's more likely to work, with the 60" LCD TV, clicking the
power button on the remote, and that would be able to
trigger a chain of events.

If I was a betting man, I wouldn't make much money betting
a person would get this working.

If you unplug the HDMI cable, *then* the laptop should
re-light the main screen. The impedance sensing generates
"events", if a cable is unplugged, or plugged in.

HTH,
Paul
Paul,

Sorry for the delay in responding. Storm came roaring through and
although we didn't have damage at the house the phone/power lines were
down for a few days.

This part of your reply is exactly what I wanted to know....

"This doesn't say anything about the power state though. The
communications are unidirectional on those wires. The video card can't
tell whether the external monitor is powered or not"

I need to learn to be more specific in my questions. The power state
was what I was interested in as I am attempting to keep the
temperature(s) of the notebook as low as possible.

Thanks
 

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