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3 Monitors Using ATI Radeon HD 6450

Last response: in Graphics & Displays
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June 24, 2013 4:44:21 PM

Am trying to run 3 monitors in Win7 Pro x64 using one MSI Radeon HD 6450 on a HP/Compaq xw8600 system. The video card has 3 interfaces; an HDMI, a DVI & a VGA.

The HDMI will not work at all when trying to connect it to my Samsung Series 5 plasma HDTV (55"). Either or both of my Acer LCD displays (20.5" & 27") will work just fine together but neither will work with the HDMI-connected Samsung.

This is especially frustrating because I was able to run my Acer 20.5" display with the HDMI-connected Samsung with my older video card (a Radeon HD 4xxx) & it worked fine when configured to "Duplicate the displays" (I use the Samsung to watch ripped BluRays).

Any asistanc would be greatly appreciated.
June 24, 2013 5:16:10 PM

video cards can only support 2 digital out-puts. how are all three monitors hooked up? you might need a active adapter
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June 24, 2013 5:45:31 PM

jbucko said:
video cards can only support 2 digital out-puts. how are all three monitors hooked up? you might need a active adapter


I would settle at this point for running the 27" Acer using the VGA output with the HDMI-connected Samsung. I can live w/o the third monitor if need be. Have tried that config & the HDMI won't work.
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a b Ô Samsung
a c 195 C Monitor
June 24, 2013 8:37:59 PM

You will need a Radeon HD card that is Eyefinity capable in order to be able to use 3 monitors. Otherwise, you can only connect 2 monitors at most. Why?

Even though a graphics card can have a DVI, HDMI and VGA ports, there is typically only on RAMDAC (Random Access Memory Digital Analog Converter). Each RAMDAC only supports to output signals so of those 3 ports only two can be used at most. Eyefinity compatible cards comes with the DisplayPort which has it's own RAMDAC, thus Eyefinity cards are capable of connecting 3 monitors (technically 4; but who's counting?).

Before Eyefinity ever appeared in the market, there were graphic cards with multiple RAMDACs, but they were relatively expensive since they were not mass produced. Anywaste, if you want to use that 3rd display, you will need to install another graphics card in an empty PCI-e x16 slot. If you do not have an empty PCI-e slot, then you must resort to looking for a graphics card with the old PCI slot (if your mobo has one), however, since there have only been small production runs they are likely to be expensive. Probably just as expensive as a Radeon HD 7750 capable of Eyefinity. But you will also need to buy a DisplayPort to DVI, VGA, or HDMI active adapter (~ $30); depending on what connections are available for that 3rd monitor.
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June 25, 2013 4:18:51 AM

jaguarskx said:
You will need a Radeon HD card that is Eyefinity capable in order to be able to use 3 monitors. Otherwise, you can only connect 2 monitors at most. Why?

Even though a graphics card can have a DVI, HDMI and VGA ports, there is typically only on RAMDAC (Random Access Memory Digital Analog Converter). Each RAMDAC only supports to output signals so of those 3 ports only two can be used at most. Eyefinity compatible cards comes with the DisplayPort which has it's own RAMDAC, thus Eyefinity cards are capable of connecting 3 monitors (technically 4; but who's counting?).

Before Eyefinity ever appeared in the market, there were graphic cards with multiple RAMDACs, but they were relatively expensive since they were not mass produced. Anywaste, if you want to use that 3rd display, you will need to install another graphics card in an empty PCI-e x16 slot. If you do not have an empty PCI-e slot, then you must resort to looking for a graphics card with the old PCI slot (if your mobo has one), however, since there have only been small production runs they are likely to be expensive. Probably just as expensive as a Radeon HD 7750 capable of Eyefinity. But you will also need to buy a DisplayPort to DVI, VGA, or HDMI active adapter (~ $30); depending on what connections are available for that 3rd monitor.

My mobo does have an extra PCI-e slot. I tried inserting my old Radeon HD 4xxx card into the unused slot & had the same results, which I will summarize below:
1) I cannot use the HDMI port at all. Whenever I attempt to plug in the Samsung HDTV to the HDMI port it will not work ("No signal" on the HDTV).
2) I can plug the 2 Acer LCD's into one card or plug them into seperate cards & both will work fine (one is plugged into the DVI port & the other into the VGA port ).
3) When I plug the Acer LCDs into seperate cards neither of the HDMI ports will work at all. (again, the dreaded "no signal")

I do have a PCI video card & an available slot for it which I can also try.

As I stated previously the HDMI port worked fine on the old Radeon HD 4xxx card when I had the Acer monitor plugged into the VGA port so am 99% certain this is a configuration/software issue. This mess started when I purchased a new Acer 27" monitor to replace the 20.5" (I didn't intend originally to run 3 monitors simultaneously). I unplugged the 20.5" Acer & plugged in the new 27" Acer LCD & suddeny the HDMI port no longer woked.

Any suggestions would be greatly appreciated!

BTW, thank you VERY much for the tutorial!
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a b Ô Samsung
a c 195 C Monitor
June 25, 2013 8:28:06 AM

Since you are not getting any video signals when connecting any of the displays to the HDMI port in both cards, that leads me to suspect that the HDMI itself could be the issue. It would be highly improbable that all HDMI ports on the displays and graphic cards is not working properly.

Try testing that HDMI cable with a different source or with a friend's setup. By different source, I mean if you have a blu-ray player try hooking the player to the HDTV using the HDMI cable in question.
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June 25, 2013 2:59:10 PM

jaguarskx said:
Since you are not getting any video signals when connecting any of the displays to the HDMI port in both cards, that leads me to suspect that the HDMI itself could be the issue. It would be highly improbable that all HDMI ports on the displays and graphic cards is not working properly.

Try testing that HDMI cable with a different source or with a friend's setup. By different source, I mean if you have a blu-ray player try hooking the player to the HDTV using the HDMI cable in question.


I have a laptop from work I can borrow that has an HDMI output on it. I will give that a try & report back.

Food for additional thought; when I boot up the PC with the HDMI cable attached I can see the BIOS screen & the "Starting Windows" Win7 startup screen on the Samsung HDTV screen. As soon as the "Starting Windows" screen disappears the HDMI goes out & I get the "No signal" error message from the HDTV. That would indicate to me that the HDMI cable itself is good-to-go.

Here's another thought; I am accessing the Acer 27" monitor through a Trendnet USB KVM switch (it's shared with 2 other computers); do you think that would make any difference?
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a b Ô Samsung
a c 195 C Monitor
June 25, 2013 9:37:20 PM

Regarding the Samsung HDTV that means there's an issue with the HDTV. I would search online to see if others have similiar issues with that specific model.

I never used a KVM so I would suggest you connect the graphics card directly to the monitor using the HDMI cable. If it works, then that means the issue is with the KVM.
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June 26, 2013 4:14:54 AM

jaguarskx said:
Regarding the Samsung HDTV that means there's an issue with the HDTV. I would search online to see if others have similiar issues with that specific model.

I never used a KVM so I would suggest you connect the graphics card directly to the monitor using the HDMI cable. If it works, then that means the issue is with the KVM.

I'm going to give that a try tonite also.

As I stated earlier, the Samsung HDTV worked fine over the HDMI cable with my old Radeon HD 4xxx card & 20.5" Acer LCD. The problem began when I purchased the new Acer 27" monitor. I even bought a new Radeon 6450 card thinking the card might be the culprit.

Thanks for your help! I'll post again when I've tried the 2 solutions you suggested.

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a b C Monitor
June 26, 2013 9:59:20 AM

tomk3212 said:

Food for additional thought; when I boot up the PC with the HDMI cable attached I can see the BIOS screen & the "Starting Windows" Win7 startup screen on the Samsung HDTV screen. As soon as the "Starting Windows" screen disappears the HDMI goes out & I get the "No signal" error message from the HDTV. That would indicate to me that the HDMI cable itself is good-to-go.

Here's another thought; I am accessing the Acer 27" monitor through a Trendnet USB KVM switch (it's shared with 2 other computers); do you think that would make any difference?


If you're able to see the boot sequence then it goes dark, that would lead me to believe its a resolution or HDCP handshake issue. If its HDCP then your KVM switch may be the culprit. I'd try to drop the res from 1080p to 720p or 480p.
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June 26, 2013 4:28:40 PM

As jaguarskx suggested I plugged the HDMI cable into a laptop w/an HDMI interface & got the same "no signal message". I then took a shorter HDMI cable & plugged the same laptop into the Samsung HDTV. VOILA! Picture (at 1980 x 1080 res) and sound. So it appears the HDMI cable is the culprit. I do have a couple of additional questions:

1) After months of being able to use the aforesaid HDMI cable why would it crap out all of a sudden when connecting a new monitor to the VGA interface on the same video card? Any thoughts on that?

2) Does the length of the HDMI cable matter? The "bad" cable is 50' long. The test HDMI cable I used is only 15 feet in length.

Many thanks to jaguarskx & all the others who posted to assist me on this!

Tom K.
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a b C Monitor
June 27, 2013 12:02:08 PM

tomk3212 said:
As jaguarskx suggested I plugged the HDMI cable into a laptop w/an HDMI interface & got the same "no signal message". I then took a shorter HDMI cable & plugged the same laptop into the Samsung HDTV. VOILA! Picture (at 1980 x 1080 res) and sound. So it appears the HDMI cable is the culprit.


You've isolated the issue, congrats. Test the cable with another HMDI source, something like a DVD player or game console. Pretty easy solution if its just the cable, they're not that expensive. It is odd that it works prior to desktop, so look for something new that may be causing interference. If another device can properly deliver an HD signal then that probably means the vid card just isn't sending a strong enough signal.

http://www.amazon.com/Tripp-Lite-B122-000-Extender-Repe...
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a b C Monitor
June 27, 2013 12:04:50 PM

Sorry for the double post. I'd still suggest testing the KVM on the sorter cable just to eliminate it from the equation.
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June 27, 2013 12:10:52 PM

bjaminnyc said:
tomk3212 said:
As jaguarskx suggested I plugged the HDMI cable into a laptop w/an HDMI interface & got the same "no signal message". I then took a shorter HDMI cable & plugged the same laptop into the Samsung HDTV. VOILA! Picture (at 1980 x 1080 res) and sound. So it appears the HDMI cable is the culprit.


You've isolated the issue, congrats. Test the cable with another HMDI source, something like a DVD player or game console. Pretty easy solution if its just the cable, they're not that expensive. It is odd that it works prior to desktop, so look for something new that may be causing interference. If another device can properly deliver an HD signal then that probably means the vid card just isn't sending a strong enough signal.

http://www.amazon.com/Tripp-Lite-B122-000-Extender-Repe...

The HDMI cable IS 50' long so that may be an issue. I also seem to remember reading somewhere that twists/bends in the cable may make a difference also. Right now it snakes around the basement next to the wall from my PC to the HDTV. I may pull it out & just run it straight across on top of the carpet as a test. If that works I may go to Plan B: a shorter HDMI straight across under the carpet from the PC to the HDTV.

Wish me luck.
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