Bios can be flashed on most boards by resetting the jumper....
If that is even the issue ( I doubt it's Bios)
In the case (however, especially if it's a custom machine, boards come with the ability to flash the bios in order to reset everything, in which case everything could (should) be fine.
* Some motherboards (Almost everyone you buy to build a custom PC) have a 3 pin jumper by the battery. Lets say that the jumper is on pins 2 and 3. Remove the jumper while the machine is off and place onto pins 1 and 2. Power on your machine let it stay on for a minute. (no you shouldn't see a post at this point). Shutdown your machine and put the jumper back to pins 2 and 3. Your reset is now complete.
Also do some tests, (it's what I would do)
Put in a PCI Video Card, A PCI-E (or AGP) Video Card, Plug in seperate monitors.
If you are using two Video Cards, connect a monitor to each, see if it's a simple case of Bios grabbing the wrong card (in Bios PCI --> Onboard, instead of Onboard -->PCI or vice versa)
Which is common when "dual screening"
If bios/Memory/anything pre OS is wrong, you will get a series of beeps, During.. (Bios Post)
Are you hearing any series of beeps from pc speaker?
Each Company can (and most times opt to) use a different series then the last, but usually you will hear 2 long beeps or 3 short beeps or etc.
Standard Bios Beeps are as follows (Generic and not nessasarly true in your case, but will give you a general idea)
1 short beep System is fine (that includes most any on board component
2 short beeps - Some sort of post error, screen will display it (if visible)
No beep Power supply or system board problem
Continuous beep could be a combination of power supply, system board, and/or keyboard problem
Repeating short beeps Power supply or system board problem
1 long, 1 short beep System board problem
1 long, 2 short beeps Display adapter problem
1 long, 3 short beeps Enhanced Graphics Adapter problem
Considering Pheonix Bios is very common, Ill include the code patters
Code:
1-1-3 Your computer can't read the configuration info stored in the CMOS. Replace the motherboard.
1-1-4 Your BIOS needs to be replaced.
1-2-1 You have a bad timer chip on the motherboard. You need a new motherboard.
1-2-2 The motherboard is bad.
1-2-3 The motherboard is bad.
1-3-1 You'll need to replace the motherboard.
1-3-3 You'll need to replace the motherboard.
1-3-4 The motherboard is bad.
1-4-1 The motherboard is bad.
1-4-2 Some of your memory is bad.
2-_-_ Any combo of beeps after two means that some of your memory is bad, and unless you want to get real technical, you should probably have the guys in the lab coats test the memory for you. Take it to the shop.
3-1-_ One of the chips on your motherboard is broken. You'll likely need to get another board.
3-2-4 One of the chips on your motherboard that checks the keyboard is broken. You'll likely need to get another board.
3-3-4 Your computer can't find the video card. Is it there? If so, try swapping it with another one and see if it works.
3-4-_ Your video card isn't working. You'll need to replace it.
4-2-1 There's a bad chip on the motherboard. You need to buy another board.
4-2-2 First check the keyboard for problems. If nothing, you have a bad motherboard.
4-2-3 Same as 4-2-2.
4-2-4 One of the cards is bad. Try yanking out the cards one by one to isolate the culprit. Replace the bad one. The last possibility is to buy another motherboard.
4-3-1 Replace the motherboard.
4-3-2 See 4-3-1
4-3-3 See 4-3-1
4-3-4 Time of day clock failure. Try running the setup program that comes with the computer. Check the date and time. If that doesn't work, replace the battery. If that doesn't work, replace the power supply. You may have to replace the motherboard, but that is rare.
4-4-1 Your serial ports are acting up. Reseat, or replace, the I/O card. If the I/O is on the motherboard itself, disable them with a jumper (consult your manual to know which one) and then add an I/O card.
4-4-2 See 4-4-1, but this time is your Parallel port that's acting up.
4-4-3 You math coprocessor is having problems. Run a test program to double-check it. If it is indeed bad, disable it, or replace it.
Low 1-1-2 Your motherboard is having problems
Low 1-1-3 This is an Extended CMOS RAM problem, check your motherboard battery, and motherboard.
Source = Pheonix Bios Company
Again , this may not be the case for your board (100% anyway) But you can find information online for your board.
Final Note:
Even though it is "the obvious" I suggest you rule out the monitor and monitor cabling, Plus make sure the pins are not bent (try it on another machine)
Secondly, Sometimes onboard graphics on that motherboard are disabled when an agp graphics card is inserted. (same goes for AGP 8X, PCI-E etc)
If the motherboard is used or refurbished the onboard might be disabled in the bios.
The quick fix is as I mentioned above, (reset Bios using jumpers) , (If you can)
Hope this helps, and saves you hassle, time and possibly money.
And worst case scenerio, Onboard Video is dead (though that would be ironic in timing don't you think?)
Plugging in a PCI-E should resolve the issue as Bios checks first either Onboard or PCI (or other) then the next in it's list to check, so therefore if the battery is good, and everything is going well, it will find the graphics card which is connected via cable), Which in theory can rule out the possibility of your onboard video card being bad, what is the probability that your batter goes, your on board card goes, and you buy a new Gforce9 that doesn't work as well?
Unless You see popped Capacitors, I don't see that being the case.