HDMI not outputting signal to VGA monitor

[Alberthan]

Hi guys,having a problem here.

Recently I wanted to make dual displays for my computer so I got a new monitor but it does not have an HDMI slot.Problem is,my computer only has 1 HDMI and one VGA(already used up by first monitor).So I went to buy HDMI to VGA and plugged into my second monitor.

Everything worked fine until windows started up,then my second monitor which mirrored my first one up until windows logo went blank.

I checked the settings and it detects my second monitor and I can even drag things there except the monitor is blank.

How I tried to fix this.

1.Update GPU driver(any other driver is not installed so if this has something to do with driver please tell me which)
2.(for future updates)

 

[Phillip Corcoran]

Do you know for sure that the GPU supports more than one monitor? What model GPU is it?
You've disclosed no system specs whatsoever, not very helpful

 

[Alberthan]

Sorry,its a radeon 4870 ,i5-750 and maxmimus 3 gene.That's all I can remember from the top of my head.

 

[Phillip Corcoran]

Configure via Catalyst Control Centre in Windows Control Panel:

http://www.tomshardware.co.uk/forum/256050-33-radeon-4870-dual-monitors

 

[Alberthan]

Quick Update: 2nd monitor ran and worked as a second display for 5-10 seconds and then pop it turned black again.

Im only using a single 4870 and I can't find a force button in my catalyst control centre.