Turn on. fans all on at start up.makes beeping noise every couple seconds. no display on monitor.(changed monitor with one I know works)still no graphics

Do you see anything on the monitor screen? Does the tower make any beeping noise or clicking noise, or does the fan tries to start up when you power the computer on? Are the cables connected properly?
If you see anything on the monitor screen, or if you hear a beeping sound, let us know so we can diagnose further.

Usually computers make beep sounds when starting up.

Do you hear any of the beep sounds?
If you hear two beeps with an interval of a couple of second, than the computer should be ok.

It could also be the monitor. Try connecting the monitor to a computer that works, or try connecting a working monitor to your computer. If the computer lights up with another monitor, then the monitor is faulty.

If the computer still is not starting up with a working monitor, than the videocard of the computer should be checked next.

Before you begin
Check the following items before using the steps in this document:
•If you have a flat panel LCD monitor, unplug the monitor power cable, wait about 30 seconds, reconnect the cable and then turn on the monitor. This resets the electronics on the monitor.
•Make sure the monitor has power - the light on the monitor is on. If the light on the monitor is off, the monitor does not have power. Connect it to a different power outlet.
•If the monitor has a detachable video cable, obtain a second monitor cable for testing purposes in case the cable is bad.
•Disconnect all connected devices except the mouse, keyboard and monitor. This includes thumb drives and camera-type memory cards from card reader slots.
With the devices disconnected, restart the computer. If the computer starts and the monitor now displays a picture, a device is preventing the computer from starting. Update the BIOS to resolve this issue.
Step 1: Connect the computer to another monitor
Connect another monitor to the computer to determine which device has the problem (the monitor or the computer). This step is very important to help you determine if the problem is coming from the computer or the monitor. If necessary, temporarily connect the computer to a friends monitor for troubleshooting purposes.
After the monitor is connected, turn on the computer and the monitor. What happens?
•If the newly attached monitor does not display anything , disconnect the cable and continue at Step 2: Is the video connection damaged?
•If the newly attached monitor displays the first startup screen(s) but then goes black, there is a problem with Windows starting. Skip to step 5 .
•If the new monitor works , the original monitor or its cables are faulty. Do the following:
1.Replace the monitor power cable.
1.Turn on the monitor. If the monitor displays an image, you are done. If the monitor remains blank, continue using these steps.
1.Replace the video cable.
Turn on the monitor. If the monitor displays an image, you are done. If the monitor remains blank, continue using these steps.
1.If the monitor does not work after replacing the cables, replace or service the monitor.
Step 2: Is the video connection damaged?
Inspect the video cable and video connectors for damage. Check for sharp bends or breaks in the cable and bent or broken pins at the connectors. With the monitor and computer off, try to straighten bent pins with a small metal tube, like the tip of an empty mechanical pencil or the tip of a retracted pen.
Figure 1: Video connector
If you had to straighten any pins, reconnect the monitor making sure that the video cable is firmly connected and then turn on the computer and monitor. If the display is still blank, continue to the next step.
Step 3: Resetting and updating the BIOS
You can use these steps even though you will not be able to see anything on the monitor.
In case an item was changed in the BIOS, such as the primary display device setting, use the following steps to reset the BIOS back to its default configuration:
1.Turn on the computer and repeatedly press one of the following keyboard keys. Press the key about once every second for 5 seconds after turning the computer on.
◦For HP and Compaq computers that came with Windows 7 and Vista, press F10 .
◦For HP and Compaq computers that came with Windows XP, press F1 .
◦For Compaq Presario desktop computers built prior to 2002, press F10 .
1.Wait another 5 seconds.
1.Press the F5 key. This restores the default settings of the BIOS.
1.Press the Enter key. This accepts the changes.
1.Press the F10 key. This saves the changes.
1.Press the Enter key. This saves the changes and exits from the BIOS.
1.The monitor should display the first screens received from the computer (the logo screens). If not, find and download the latest BIOS update if one is available for your computer.
1.If a BIOS update was not available or the monitor is still blank, continue to the next step.

That beeping noise may be due to over heating.
Most machines today have a temperature setting that will turn the machine off once the temperature reaches a certain point.
Safety feature to avoid damaging your cpu and components.
The shut down and restarting allows the CPU to cool down briefly.
Thus allowing you to start the machine again. Usually it will shut down again once the temperature threshold is again reached.
Good test is let the machine sit for 30 min. If it immediately starts up and shuts down a few minutes later. Heat build is usually the problem.

Typically this is due to heat sink or Fan on the computer CPU.
Check to be sure both are connected to the CPU and functioning.
If you have a fan on top of the heat sink above the CPU. Make sure it is working correctly. Dust build up over time will eventually kill the fan bearings or reduce airflow. Heat sink can and will become clogged with dust also. Replacement fans are easy to find. Heat sinks are even easier to clean.
Depending on your machine and CPU position replacing the fan can be a challenge. But can be done in a few minutes with minimum tools.

Each bios has different post codes and it is difficult to tell what is happening with out knowing the bios of your particular machine. Listen for the beeps and check your computer manual.
You can also google for this. Here is a web site that lists a few bios P.O.S.T codes.
http://www.computerhope.com/beep.htm
Once you know the beep sequence you can look it up. Usually points to the problem and you can go from there.

Good luck!

Did you your CPU Fan inside, that's the one who make some noises inside.
If your computer is failing to start then check CPU inside, all the peripherals double check on it. From VGA Card, Memory and other devices, maybe its not properly connected inside. Good luck!

Remove all data cables and external cards and press RAM than try again

Ebay has always been there for me but it is risky. Make sure you know what your bidding on. Do your research. Pricewatch.com is another. Also make sure the settings in your bios hasen't changed. Set all values to Default may also help. Hope this helps.

1) You need to change your memory, the may be bad, and it will not display anything on your screen.
2) Make sure that your processor fan is well connected

Jowinson

If there is long beep it means you have problem in your memory.

• To fix this type of problem, Remove RAM clean its connection point and place it again. If still problem then you should try new RAM.

Thanks
Iqbal

you may be knowing there are many types of beeps which made as standard for all pc ...
if the pc beeps for 30 seconds and then starts means there is no input device connected ...(here the standard input device is keyboard)
so c the keyboard is connected properly or not try reconnecting it...
and about the display when sometimes computer makes beeping sound the screen is not displayed ... after connecting that just try is it working or not.. if problem persists then just check the cables of the monitor too... try reconnecting them also.....