johns said:
I tried using a dvi splitter on just the first dvi port .. one to
monitor, one to hdmi ( dvi to hdmi )
port on the tv. Whooeee! That did not work at all. The tv generated
some kind of goofy
problem with the card clock, and the whole thing went nuts. So, is it
possible to put
the tv on the 2nd dvi port on the back of the 275, and tell that port
it is going to a tv ..
without goofing up the first port timing and frame rate going to the
monitor ? I would like
to be able to choose which one I'm using, and shut the other off
without disturbing the
setup ... just want something like a desktop icon to choose which
monitor.
johns
The high speed digital signals consist of "data+" and "data-".
The two signals behave the exact opposite of one another. And,
that's called differential signal transmission. The signals
are normally terminated by a single resistor across the two signals,
on the receiving display device.
Simple-minded passive splitters, they send "data+" to one monitor, and
"data-" to the other monitor. The signal level is around half of
the normal amplitude.
A better solution, is an active buffer.
http://www.gefen.com/kvm/dproduct2.jsp?prod_id=3571
There is one DVI in, and two DVI out. Of the two DVI out,
one is designated the "primary" output. The EDID (resolution
table) of the primary monitor, is used by the OS when it
comes time to select a resolution. The EDID of the second
monitor is disconnected. The second monitor is "slaved"
(not in control of its own destiny).
In order for the slave to receive a valid signal, you have
to find a resolution that both display devices share.
With the primary device only connected, you use the Windows
display control to set the display to that "common" value.
Then, when the secondary display is connected to the second
connector, it receives a valid signal right away. (It isn't
that important to do it that way, and I'm mainly explaining
this to give some idea how it works.)
If you just connect both monitors, and select a resolution
to drive the Primary display, without thought to the
secondary, then the secondary will pop up its OSD
and say "Out Of Range" to the incoming signal. When
a resolution they both share is selected, then both
screens will have the same content viewable.
That works better than the missing "mirror mode", removed
from the Nvidia driver years ago.
Summary: Buy an active buffer. Read the manual for it
before you buy, to understand how it works.
Note - when I use a Gefen product as an example, it
doesn't mean to run out and buy one. Gefen stuff is
expensive. The above box is $350, and has its own
wall adapter. There's no particular reason such
a box should cost $350. Look around.
Here's one for $80. Users aren't that pleased, perhaps
because the manual sucks and didn't explain things well ?
http://www.newegg.com/Product/Product.aspx?Item=N82E16817422028
That one includes a power adapter, so you know it's "active"
and not a ripoff "passive" type.
OK, the manual has no details, as to which output connector
is the "primary" and has the EDID connected to the computer.
So this is a "buy and pray" product.
http://aluratek.com/cms/legacy/downloads/ADS02F-ADS04F_QSG.pdf
*******
At the $350 price point, not only would I expect a DVI splitter,
I would expect a scalar as well. In the crappy example I made
up below, the scaler scales the output to a lower resolution that
the secondary monitor supports. The secondary monitor EDID is
read by the scaler. The primary monitor EDID is read by
the computer. This is the kind of function I'd expect for
$350.
Computer ---- 1920x1080 ------ splitter/scaler ----- 1920x1080--- primary
|
+---- 640x480 --- secondary
To just digitally buffer the DVI signal, shouldn't cost
$350 to build. Unless, of course, you're running it
through a scalar, and leaving the resolution the
same anyway. (Effectively null digital regeneration.)
*******
Perhaps what you're looking for, is a KVM of some
sort, if you seek to randomly turn off one of the
monitors. But a KVM doesn't generally "broadcast" to
two monitors at the same time. So a KVM is not a splitter,
and a splitter is not a KVM, if you get my drift.
It's possible if you go to a KVM manufacturer site, you
can find something that does what you want.
You can undoubtedly get the function you seek, for
$1000 or so. But for less money, you can get something
approximately "good enough".
It really all depends, when the primary monitor has its
screen switched off with the soft power button, whether the
EDID remains available or not. In theory, the EDID should
still be working. But we can't be sure of that, and perhaps
instead the secondary monitor goes nuts and the resolution
is set to something silly. So while the active splitter
may come very close, there might still be monitor mixes,
where you'll need to leave the primary powered up.
Anyway, even if I didn't do a good job of answering
your question, at least dump the passive splitter.
Because it's just a bad idea.
Paul
