Dual screen setup, 2nd won't go to standby

[Rajagra]

Long shot, but may as well ask...

I have a PC with 2 GTX280 video cards in SLI, going to 2 screens. Both screens plug in to one video card (only option, and each card has 2 DVI connectors.)

Before, when the PC was turned off, both screens went into standby, as they should.

While diagnosing a fault, I swapped the two cards around. As they are identical, including firmware, everything should have worked the same.

I seem to have resolved the original fault, but now when the PC is off, the 2nd screen doesn't go into standby any more - it goes into a self-test mode, as if the cable was unplugged.

(As an aside, this also happens when I switch the screens to another PC that uses VGA connections. I thought this may be a limitation of the VGA.)

The question is, why do some cards send both connected screens to sleep, while others cause the 2nd screen to act as if disconnected? To repeat, two cards are absolutely identical.

I will probably swap the cards round again and hope the original fault doesn't recur in the process.

[Infinite north]

Are both monitors plugged into one card? or have you tried updating the drivers yet? a third party program like ultramon might fix it.

[Rajagra]

Yes, both screens have to be plugged into the primary card. Drivers were the latest a few days ago.

I swapped the cards around, everything works properly now. Checked the labelling while I was at it, same details. GPU-Z shows them as identical.

I think some nVidia cards just have a dodgy second connector, they figure nobody will ever notice.

[Lanx]

never had this issue from either nvidia or ati, been rocking dualscreens since you had to install a seperate pci card for one.

[zefrer]

My guess would be the drivers need re-installing after you swap cards.

[Ekaros]

Umm, I can't see how this would be driver related issue... Likely a connection issue, might be other port is bad one, or cable wasn't properly plugged.

Hmm, I think even having the monitor connected to any port makes difference between cable plugged and un-plugged. Don't know DVI or VGA specs, but likely there is some loop between monitor and card...

[D-EJ915]

Make sure DVI power management is enabled on the monitor.

[microsoft windows]

I'd just shut off the monitor when I'm done using it if none of this works. It would probably take less time than trying to get it to go into standby properly.

[Rajagra]

I'd just shut off the monitor when I'm done using it if none of this works. It would probably take less time than trying to get it to go into standby properly.

The trouble is turning off power to the screen turns of its USB hub, which can have adverse effects - like waking the PC from standby!

Everything is OK now I swapped the cards to their original positions. I think the driver theory is plausible - maybe it reads the graphics card serial numbers, so even though they are identical hardware, it configures them differently?

But that wouldn't explain why my other PC has a similar problem over VGA. It has a single card with dual ports, has done from day one. (Though I changed from DVI to VGA ports.)

A minor fault on the secondary ports of some cards looks like the cause still.

[Ekaros]

Umm, I can't belive there is anything to do with drivers. Have to test once I get to my other computer in weekend, but I belive atleast on VGA monitor goes to stand-by when it's plugged in, even if it's connected for first time...

Ah, there is +5V and ground for it, for monitors stand-by... 14th and 15th pin(middle of connector in main group second and third from the -/+).
So, connector is likely bad...

[Rajagra]

I may have solved the mystery.

I started by testing the second monitor in all of the 4 possible sockets, even ones that weren't allowed before. Not only did power save work properly, but I discovered the latest drivers allow you to use any sockets you please and still run SLI. Well done, nVidia.

I unplugged the graphics cards from the PC. Plugging the monitor into any socket still enabled power save, even in the suspect socket!

I reinstalled the cards in the order that caused the problem before. I couldn't replicate the problem.

But ... during the earlier testing I noticed in nVidia's SLI configuration page that the S-video connector was shown on just one of the cards. Now, neither card shows the S-video socket.

I think video output had been enabled at some point on one card, and that messed up the secondary DVI socket - insofar as it worked properly for output, but power saving was broken.

[microsoft windows]

The trouble is turning off power to the screen turns of its USB hub, which can have adverse effects - like waking the PC from standby!

Everything is OK now I swapped the cards to their original positions. I think the driver theory is plausible - maybe it reads the graphics card serial numbers, so even though they are identical hardware, it configures them differently?

But that wouldn't explain why my other PC has a similar problem over VGA. It has a single card with dual ports, has done from day one. (Though I changed from DVI to VGA ports.)

A minor fault on the secondary ports of some cards looks like the cause still.

I've always found those USB hubs built into things like monitors and keyboards to be more of a hassle than they're worth in my situation. Most of them only give you one more USB port total and require another cable. Most computers these days tend to have plenty of USB ports anyhow.

[Rajagra]

I've always found those USB hubs built into things like monitors and keyboards to be more of a hassle than they're worth in my situation. Most of them only give you one more USB port total and require another cable. Most computers these days tend to have plenty of USB ports anyhow.

I felt the same at first. But these screens (Dell 2405FPW) have 4 USB 2 sockets, and 4 memory card slots. Well worth plugging in a single cable to get all that functionality. I kicked myself for not using them for the first year or two of owning them.

[elservo]

So you installed the latest drivers and that fixed it?  Kind of amazed that worked!  Oftentimes I'll install a new driver and my PC will tell me the new driver won't work with the hardware specified.  I find that informing the computer that it's for the hardware specified does nothing.  I then uninstall and reinstall the new driver and it works.  PC's just love to mess with me.

[Rajagra]

Ah, no, I had already installed the latest drivers before all this. I just hadn't realised they allowed any combination of outputs to be used.

I think what fixed it was when I told the nVidia control panel to do a rigorous scan for new displays. It found none, but asked if I wanted to enable extra outputs anyway. I said no. I believe that disabled s-video socket and returned the 2nd DVI port to normal operation.

Either that or juggling the two screens between the four DVI sockets while powered up forced it to work out the real state of affairs.

[microsoft windows]

I felt the same at first. But these screens (Dell 2405FPW) have 4 USB 2 sockets, and 4 memory card slots. Well worth plugging in a single cable to get all that functionality. I kicked myself for not using them for the first year or two of owning them.

Memory card slots? Now that seems actually useful!

To tell you all the truth, I never really use USB for some reason. I never use flash drives (I transfer files over my network or with floppies and CD's instead) , and all my mice and keyboards and printers are all too old to be USB.

The only things I use that run off USB are wireless cards for computers with broken ethernet cards.

I used to use USB a lot more back before my flash drive bit the dust, but I've never really felt like replacing it yet (But those stinking things keep getting cheaper and cheaper these days).