Windows 7: Toshiba p505s8000 fail to boot with 2 beeps

My Toshiba P505 fails to boot,gives 2 beeps.No other activity,no hard drive activity, no display.Power light says on,and it will turn off by power button.
Removed battery, still the same results with power brick only.
Thanks in advance for any help on this problem.

Test RAM - Test with Memtest86+ for 5-6 passes following steps in blue link to test both RAM and slots.

Swap your RAM sticks, try with only one stick at a time placed in slot closest to CPU.

Next check that HD is detected in BIOS setup. If not try reinstalling it checking contacts. If so boot and run the maker's HD Diagnostic extended CD scan.

If this doesn't help then work through Troubleshooting Windows 7 Failure to Boot.

I was called away from desk for a few hours, and left the troubled computer on,with battery removed,and powered from a/c brick.
When I returned, everything was working normally.No error messages.
For time being, problem seems to have cleared while testing, but time will tell if it occurs again.
I have made notes on the offered advice and will try these if the problem occurs again.
I will keep this open for a few days just in case.

Thanks for all of your valuable time and effort on this problem.

I tried rebooting this morning, after it sat all night.After about 5 failed attempts,it booted up and acted normally.I shut it down, and it is right back to same problem of no boot up.There are no beeps, but it does attempt to read the dvd drive,but does not try to access hard drive.Screen is black.
I tried letting it cool for a couple of hours, thinking maybe over heating but to no avail.Fan is running.
Cannot access safe mode or anything on screen.
I have reseated and swapped memory chips, no difference.
Killed power at wall outlet in case power supply had crow barred.No difference.
As always, I am very thankful for all assistance on this problem.

Then try everything in Troubleshooting Windows 7 Failure to Boot,
starting with the hardware tests.

Is HD detected in BIOS setup? Reset BIOS to defaults after noting SATA controller setting: Clear CMOS - 3 Ways to Clear the CMOS - Reset BIOS

My built in monitor is totally black.Cannot access anything to try tests.
What else can I try?
thanks

Try plugging in an external monitor to do the repairs.

External monitor also shows no signal.I removed hard drive, and it is readable from another computer via USB-SATA adapter plug.Cannot troubleshoot without working monitor.
Any suggestions?
Thanks for your patience.

Is the mobo starting and showing activity via it's LED light? Is the fan working? You may need a new GPU chip or mobo. If it was only the screen then it would display on an external monitor.

Power light comes on, but no hard drive activity light.It does try to access DVD drive initially,but not hard drive.Cannot get to cmos setup to change boot drive because of no video output.My hands are kind of tied at this point.