What's the difference in old and new video cards?

[BDawg]

A couple of days ago, I screwed up the BIOS on my computer and it refused to post. I would get absolutely nothing on my screen through my Radeon x800XT.

While I was troubleshooting, I read someone's post that he was able to get into the BIOS repairer by putting in an old video card. I put in my old GeForce3Ti200 and sure enough, I got video and saw the BIOS repairer.

After reflasing my BIOS, I put the x800XT back in and now everything's good.

What is it that makes new cards not function in a situation like this, but old ones work fine?

 

[Peter]

You might have picked a "special" configuration item that crashes one card but works (or is irrelevant) with the other.

 

[BDawg]

Originally posted by: Peter
You might have picked a "special" configuration item that crashes one card but works (or is irrelevant) with the other.

I guess I should've been more specific... I tried updating my BIOS and it failed. When I rebooted, it wouldn't post. With the x800XT, no video, with the GF3Ti200, I got video and was able to enter the BIOS repair function.

 

[Peter]

Sort of still the same answer then - maybe your failed BIOS update broke a piece of code that's needed for the one card, but which isn't being executed for the other.

Inside a system BIOS, there's no inherent difference in VGA card handling, just workarounds for peculiarities of specific cards or chips. The device specific part is contained within the VGA BIOS on the card.

 

[apoppin]

Originally posted by: BDawg

Originally posted by: Peter
You might have picked a "special" configuration item that crashes one card but works (or is irrelevant) with the other.

I guess I should've been more specific... I tried updating my BIOS and it failed. When I rebooted, it wouldn't post. With the x800XT, no video, with the GF3Ti200, I got video and was able to enter the BIOS repair function.

if you update your MB's BIOS and it fails, the same thing will happen if you cannot flash it back ... it is a "dead" piece of HW
http://www.badflash.com/biosupdate.htm
http://www.badflash.com/biosupdate.htm

here is good info on Video Card BIOS flashing and recovering from failure:

http://www.benchzone.com/forum/viewtopic.php?f=75&p=636

and a good article which included step-by-step instruction to recover:
Guide to Video BIOS flashing

The video is BIOS is a small piece of code (typically <64 KB), which is stored inside a small chip on your video card. When the VGA card receives power, the BIOS is loaded into system memory and immediately executed by the CPU.

On startup, the BIOS initializes the video card:

* Initialize the GPU
* Detect number of memory chips, chip size, access mode
* Enable memory access and set proper timings
* Detect if external devices (analog VGA, DVI, TV-out) are connected and enable them
* Set core and memory clock
* Enable power management
* Set fan speed (if supported by the board)

After these tasks are completed, the display will turn on and display what's happening next - usually the motherboard's POST screen.

Once you boot into Windows, the display driver takes over all video functions and the BIOS is no longer used. However, it remains accessible for execution. Actually, manufacturers like ATI added a handful of functions which can be invoked from within Windows, for example to change power management settings on a mobile GPU.

 

[coolpurplefan]

Do you mean the BIOS for your video card or motherboard?

 

[apoppin]

he meant his Video card ... i just posted the "parallel" to what happens when your MB flash goes bad

he wanted to know "what goes on" in the BIOS

 

[BDawg]

Originally posted by: coolpurplefan
Do you mean the BIOS for your video card or motherboard?

Again... I wasn't specific enough. It was my MB BIOS. When I did an update, I borked the thing and couldn't get any POST behavior. With the x800XT, I couldn't see anything. When I hooked up the GF3Ti200, I got to the MB's BIOS repair utility that's supposed to appear in the even of a borked MB BIOS.

Sorry for not being specific.

 

[BDawg]

Originally posted by: apoppin
he meant his Video card ... i just posted the "parallel" to what happens when your MB flash goes bad

he wanted to know "what goes on" in the BIOS

I know what's going on in the BIOS. I just don't get why when I had a bad MB BIOS, the newer card wouldn't show anything, but the older card would.

Nothing happened to, or changed in either video card.

 

[xtknight]

If it was hooked up to an LCD, one card may have the LCD/DVI POST bug where nothing displays.

 

[BDawg]

Originally posted by: xtknight
If it was hooked up to an LCD, one card may have the LCD/DVI POST bug where nothing displays.

It was plugged up to an LDC through DVI. But, so was the second card.

 

[Peter]

No need to lecture me about what BIOS does what ... I'm a BIOS engineer, and I've been one for a decade.

The system BIOS just goes,

* Let's see if we have a VGA card.
* First one that is found gets standard VGA resources assigned, and whatever other memory, I/O and IRQ resources it requests.
* Copy its VGA ROM into shadow RAM in the location where ISA VGA cards used to have their ROM
* Jump into VGA ROM entry point

At this point, control is in the VGA BIOS. That VGA BIOS does what you quoted, and then (hopefully) returns control to the system BIOS.

The system BIOS then uses VGA BIOS services to paint the welcome screen and display POST results.

 

[apoppin]

Originally posted by: Peter
No need to lecture me about what BIOS does what ... I'm a BIOS engineer, and I've been one for a decade.

good heavens, i hope no one was attempting to lecture you

what i [finally] figured out what the OP is asking is WHY would one older GPU boot up and the other newer one won't? - in the same messed-up MB


--and are you the guy i need to see if i ever need a BIOS rewritten or edited?
:Q

 

[BDawg]

Originally posted by: apoppin

what i [finally] figured out what the OP is asking is WHY would one older GPU boot up and the other newer one won't? - in the same messed-up MB

Yes... I like how you were able to say that in 1 sentence.

 

[apoppin]

Originally posted by: BDawg

Originally posted by: apoppin

what i [finally] figured out what the OP is asking is WHY would one older GPU boot up and the other newer one won't? - in the same messed-up MB

Yes... I like how you were able to say that in 1 sentence.

thanks ... then Peter's answer should still stand:

- maybe your failed BIOS update broke a piece of code that's needed for the one card, but which isn't being executed for the other.

Inside a system BIOS, there's no inherent difference in VGA card handling, just workarounds for peculiarities of specific cards or chips. The device specific part is contained within the VGA BIOS on the card.

Peter got it right away!