I apologize for all of the inconveniences you've had with the Intel(R) desktop boards you've owned.
Regarding the current problem, as I understand your Intel(R) Desktop Board DH55HC no longer POSTs; it only beeps twice, pauses, and then, beeps, again, twice, but does not go further than that, and this happened right after you install the x1 PCIe* nVidia* card. If that's correct, to begin troubleshooting, I'd recommend trying with the minimum system components.
Reminder: A basic computer configuration would consist of the following: keyboard, mouse, processor, memory, hard drive, CD-ROM, video card, and monitor. No other add-in should be installed.