quarta-feira, 30 de outubro de 2013

Motherboard Boots with Blank screen until Windows or Linux starts

I have a Geforce 7600 GS with two ports, VGA and DVI, on a Gigabyte 965P-DS3 rev3.3.

My monitor is a Samsung SyncMaster P2370 (2ms/50000:1/16:9/1080p/DVI)

Until recently I was using the DVI-VGA cable to connect the Monitor DVI to my Geforce VGA port.

But, I started to get into arduino/RPi/uC testing and having another monitor on my desk became a big problem, I started to run out of space.

HDMI Switch
So I though I could just buy a DVI to HDMI adapter for each end and use a HDMI cable to connect my Monitor to my Graphic card, as easy as that, in this way I could do some cable swapping and have my Raspberry Pi connected just as fast with a HDMI switch.
DVI-HDMI adapter

Well I started by getting the DVI-HDMI Adapters to give it a try.  So I disconnected the DVI-VGA cable, installed the adapters and connected the new HDMI cable.

When I turned on the system....
no screen...but what!

After booting the Windows/Linux screen showed up at the login.

What the heck!  No boot screen ?!?!  I can't really live without boot screen!

So I started to research the blogs, news groups, and other chats to check similar bugs!

I found many similar problems with Windows 7 and Nvidia, as well as patches, mess with the bios, tips to undo updates, and many more procedures.

After a few days, with no solution found, I sad to my self, what the heck, just install the HDMI switch (I used a double face tape to glue it the the back of my Monitor) and lets just test the original plan.....and, behold! the boot screen is back! Hooray!

How this is possible ?

After some study about signals and HDMI standards, I concluded that the problem is with signal polarity, since we use the same type of adapter for both the Monitor side and also for the graphic card port.  When the HDMI switch is in place, it corrects the balanced line polarities and that's it!

Conclusion: there should be a DVI-HDMI adapter for each side of the connection (which is not available, by what I know).  And building your own HDMI cable is not very simple, and quite difficult to get the parts and hardware tools.

The HDMI switch I bought is this one:


The short HDMI cable I used to connect the Monitor to the HDMI switch is this one:


I used a additional short HDMI cable to leave it connected to the second port of the HDMI switch to connect my RPi or other systems as needed.


MS/Nvidia/Gigabyte/others should pay us to solve their problems, and Amzn should help us too!