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PowerMac G5 Quad with HDMI and a Switch

MacCubed

MacCubed

macrumors 68000
Original poster
Apr 26, 2014
1,618
494
Florida
Today I finally got around to getting a HDMI switch for my TV. The TV sits on my desk and has 2 HDMI ports, I use my Xbox, Quad, and Apple TV with it. I spent a good hour trying to figure out what was going on... Here's what happened, originally, I had the Xbox and the ATV plugged into the switch, the Xbox worked fine, but the Apple TV wouldn't come on. I assumed that this was an issue with power, since the switch is driven by HDMI, I then swapped the Apple TV with the Quad and it worked fine, until I turned the Quad into sleep. Then there was no signal on the TV when I woke it, but the Xbox worked fine. Eventually, I found out that one of the HDMI ports on my TV is a bit bad, so that saved some headaches. Now here at the end of the day, I have the Xbox and Apple TV plugged into the switch, and the Quad plugged into the other HDMI port on the TV. I have no idea why the Quad won't work on the switch, but works fine on the other port. I tried to use other cables to output the signal from the switch, I tried to use the other port on the graphics card, I tried a reboot, and I tried other combos with the Xbox/Quad/ATV on the switch. I would like the Quad and the Xbox to be on the switch, as it does not support HDCP which is required for Netflix playback. Another thing, when I had the Quad plugged in to the switch, I tried screen sharing to mess with the resolution, but the TV isn't even detected.
 
I wouldn't recommend auto-sensing HDMI switches, older GPUs don't "ping" and are prone to remaining in sleep or dropping into VGA-ish resolution compatibility mode as the handshake of resolution status with the TV is missing. Some older HDTVs don't work with switches/computers over HDMI, a family members' 2007(?) Sony Bravia(pre-SmartTV) HDMI ports don't work on computers so you must use the VGA port instead :(

If you're using a physical button HDMI switch, some GPUs prefer the TV pre-switched before waking up/turning on--my 2010 MBP w/GeForce 320M will get stuck at 800x600 2nd display mode if it wasn't pre-switched.
 
So, the ATV and the G5 both work fine when they're plugged directly into the TV (leaving the Xbox out of the equation for the time being)?
 
Xandros said:
So, the ATV and the G5 both work fine when they're plugged directly into the TV (leaving the Xbox out of the equation for the time being)?
Click to expand...
Yea they work fine. As of now, I have the Xbox and the ATV on the switch and the Quad in the TV
 
I expect you've tried this but does it work in this specific order (with the G5 and xbox plugged into the switch):

Turn off the tv.
Switch to the G5 on the switch.
Wake up the G5.
Turn on the tv.
 
Xandros said:
I expect you've tried this but does it work in this specific order (with the G5 and xbox plugged into the switch):

Turn off the tv.
Switch to the G5 on the switch.
Wake up the G5.
Turn on the tv.
Click to expand...
I will try ot right now, I'm also gonna test my DLSD with the DVI>HDMI
 
Ok just tried the DLSD, and no dice. I think the computer isn't supplying enough power to the switch
 
Certainly sounds like lack of power in that case. If you've got a quad, how are you connecting it via HDMI - did you replace the graphics card with one that has HDMI out or are you using an adapter on the existing card's DVI port?
 
Xandros said:
Certainly sounds like lack of power in that case. If you've got a quad, how are you connecting it via HDMI - did you replace the graphics card with one that has HDMI out or are you using an adapter on the existing card's DVI port?
Click to expand...
I have a HDMI to DVI cable that connects from the GeForce 6600GT to my TV or the switch. I think there is no power coming through DVI as displays don't drive themselves. I wonder if an ADC to DVI and then the HDMI to DVI would work since ADC provides power. But I'm not sure that any PCIe cards have ADC. If the switch had a power supply I would be fine.
 
That may be the problem then. As far as I know DVI does specify pin 14 as being a +5v rail, but it can only be a maximum of 50mA. HDMI on the other hand has pin 18 as the +5v rail but specifies it as being a minimum of 50mA, meaning device manufactures can (and do) exceed the spec to provide more current over pin 18 for devices like self-powered switches, but it isn't generally considered "good practice" for them to do so. Or something like that anyway.

If your switch can function on 0.05amps then, there's a chance the reason it doesn't work is because your adapter doesn't have pin 14 wired up (so there is no power going to pin 18 on the HDMI side). Of course, the chances the switch can function on just 0.05amps is highly unlikely.

Edit: After a quick glance at the ADC pin layout, it has two 25v pins, no 5v pin, so you'd have the exact same problem because any adapter you bought simply won't have it's 5v pin powered (because there's no equivalent 5v pin to power it with from the ADC side).

Your only option is to buy another switch that is externally powered to overcome this problem.
 
Last edited:
There are, they're mainly used for audio I believe. Expect to pay more than a new switch costs for one.
 
I figured it out. The HDMI cable that was running from the switch to my TV was a bit broken, so it didn't have enough power to drive the Quad and the Xbox. I swapped cables cause I wasn't getting sound on my Xbox. Now Im gonna swap cables around again to get HDCP on the ATV!
 
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