PC powers on, fans spin, infinite 1 second beeps, no video output - removed vid card with PS switch on, computer off

[lucidhate]

Hi (specs at bottom),

I started with a working setup. But the fan was loud on the graphics card so I was looking to oil it.
I left my power cable plugged in for a ground, but forgot to switch off the PS and removed my PCI-E 16x graphics card. The computer was not physically running, but power was available. Since then, I do not get any output, just a black screen or 'no input' displayed depending on the monitor/TV tried. But, the PC powers on, fans spin, no video output.

I get the following beep code:
1 (full) second long beeps, infinite times, 2 seconds apart

According to my motherboard manual this could be one of these two:
Continuous long beeps: Graphics card not inserted properly
Continuous short beeps: Power error

What is considered 'long' vs 'short'? I know the graphics card works (see below) so it's either the PCI-E slot itself, or the motherboard as a whoie, or the PSU. Any ideas on which one?

What I have tried (which has not made any difference):
-installing a brand new card PCI-E card
-installing a known working older PCI-E card
-moving all 3 cards to the second PCI-E 4x slot
-plugging the monitors into the onboard graphics instead (note, If i remember correctly, these did not work previously, so no real hope there, but tried anyway. They were DOA with the mobo but I planned to use an external card from the starts so it didn't bother me)
-resetting the CMOS (via battery/jumper)
-all of the above with the PCI-E card in the slot and removed (to try to trigger onboard graphics)
-all options for output (DVI, HDMI, VGA)

I don't see anything burnt on the mobo or bent pins.
I didn't see a spark when I removed the card or hear a noise.

Note: The GPU fan does spin so some sort of power is getting to the PCI-E slot. And the graphics card does not need/use any external power.

What I have not tried:
-a new power supply (don't have an extra)
-replacing the mobo
-removing and checking the CPU (don't see this as a possible issue)

I am hesitant to replace the mobo with a newer setup, or rebuild the computer as I need this installation/configuration of windows to boot. And, I know sometimes that does not work when the hardware is changed. I could replace it with the exact same mobo, but have no idea where to find this older model (except refurbished on ebay, which concerns me).

Here are the specs:

Display:
PCI-E:
GeForce GT520 2G
also tried another one of the same
and a 1GB version
Onboard:
Video Adapter ATI Radeon HD 3200 Graphics

OS:
Windows 7 32 bit

CPU Properties:
CPU Type 2x
CPUID CPU Name AMD Phenom(tm) II X4 940 Processor
CPUID Revision 00100F42h
CPU Speed:
CPU Clock 3013.90 MHz

Motherboard:
Manufacturer Gigabyte Technology Co., Ltd.
Product GA-MA780G-UD3H
https://s3-us-west-2.amazonaws.com/www.mrcdn.com/pdf/gigabyte/gigabyte-ga-ma780g-ud3h-rev-1-0-owner-s-manual.pdf

RAM
6BG of DDR2 (only 4 used)

 

[lucidhate]

I ended up buying a new power supply to test it out as a fix. It did generally fix the computer. However, there was a continuous beep (highly obnoxious) on boot after the replacement. It was not a long beep or a short beep with intervals, just a continuous rapid firing beep. I ended up disabling the moniot system fan option in the bios as the computer appears to run fine. All the fans are running properly. Still curious about the beep, as not in mobo manual. My guess is it's either a mobo malfunction or the CPU is overheating.