The computer powers on but the screen is blank. When I hook up an external monitor, it works fine. It's an HP dv9930us.

Most laptops have a "toggle":
* output video only to internal LCD screen,
* output video only to external HDMI port,
* output video to both internal & external.

Set the "toggle" to the best value.

Can you hook the computer up to an external monitor? If you have a desktop monitor that you can hook it too it could help determine if the LCD panel has failed.

When you turn on the computer, if you can see the harddrive light flickering/blinking then the computer is going thru the motions to boot up and it is just a visual issue. Purhaps your video card has failed. I know that HP / Compaq has had problems in the past with the Nvidia GPU seperating from the motherboard when they get too hot and the screen will go blank.

Try to hook to a external monitor and let me know your prognosis.

Hook a external monitor to the video output on the back of the laptop, if monitor works, it means that the laptop screen has a bad inverter board or back light issue. If the monitor has a blank screen like the laptop, the video graphics card is bad, or you have motherboard problems, suggest a computer tech.

This could be due to presence of static charges on the notebook or hardware malfunction of the video card or defective LCD display screen of the notebook. To resolve the issue, perform the following steps.
Step 1: Hard Reset
To perform a hard reset, please follow the steps listed below:

1. Unplug the AC adapter from the notebook PC and remove from any port replicator or docking station.
2. Remove the battery from the notebook battery compartment.
3. Press and hold down the power button for about 20 seconds.
4. Insert the battery and plug the AC adapter back into the notebook PC.
5. Press the power button to turn the notebook PC back on.
This will discharge the static charges from the notebook. Now check if the display works fine or not. Incase, if the issue persists, then the video card or LCD screen must have gone bad, and to isolate the same, please connect an external monitor to the notebook and check for the display on it. You can follow the steps below to connect an external monitor to the notebook.
1. Turn off the notebook.
2. Connect the monitor cable from the external monitor to the monitor port on the rear/side of the computer.
3. Connect the monitor to a power source and turn it on.
4. Press the Power button to turn on the computer.

At this time, please follow the instructions mentioned below for switching the display to the external monitor:

The notebook's video card supports three modes. Built-in screen only; external video only; and both on simultaneously (mirrored). If you're not seeing the image on the desired device(s), the notebook's video card is probably in another mode. Press FN + F4 to cycle through the display options: Notebook display, External monitor, both.

If you press FN + F4 once, the external monitor will display & there will be no Notebook LCD display.
If you press FN + F4 twice, the external monitor will display & there will be some shading on the Notebook LCD.
If you press FN + F4 thrice, both Notebook LCD & external monitor will display.

If the issue persists on the external monitor, then this could be due to defective video card on the notebook. However, if the display on the external monitor is fine, then the issue is with the LCD display panel of the notebook. In either cases, the notebook requires a detailed onsite diagnosis by a service technician.

If your notebook is under HP warranty, then contact HP to get the notebook repaired for free of cost.

The laptop has a built-in video card and the video RAM uses part of the main RAM.
First, re-seat the RAM modules and if the laptop still does not boot up normally then remove the RAM and get it tested at your friendly computer repair shop.
If the RAM is OK then connect an external monitor to the laptop, power up the monitor first and then the laptop. The video data should divert to the external monitor automatically, if you do not get any video image on the monitor then the video card in the laptop is faulty and a motherboard replacement is required.
A replacement motherboard may not be a cost effective solution and If it was me, I would put my money on a new laptop. I would then remove the hard disk and insert it into an USB adapter case and use it as an external USB hard drive.

Power drain would be a better solution in this case.
1.first shut down the comp
2.unplug the charger
3. remove the battery
and after press and hold the power button for 60 seconds without any charger and the battery.After the 60 seconds replug the battery and the charger and turn the computer .

Hello, I'd start by hooking up another external monitor, that way you can rule out if your video/graphics card is working. If the new monitor works that means your video card is fine and you'll need to look at replacing your current monitor Good luck, mpawlak908

If it still doesn't work when you hook it up to an external monitor, assuming you did that properly, then it is your motherboard/video card.

If you have a seperate video card, I would replace that first. If you don't have a seperate video card, then you need a new motherboard.

FIRST - I would try hooking it back up to an external monitor, and making sure you switch it over to use the external as the default. otherwise you wont get picture.

Sorry... good luck.

your gpu has failed - thats graphics processing unit. new m/board required

I think Your computer C.P.U. power supply unit is not working properly. because these type of problem occur when Power Supply Unit is not working properly.........

So Don't afraid at all just change your c.p.u. power supply unit with new one (it is not costly at all).