In reading your post, I think the assumption "The card does have the 6 pin power connecter socket but as I use my pc for normal and not gaming use it should still run ok on the PCI socket for power?" is what is causing the problem.
I did find one of that type card without the 6pin additional connection, but since the one in question does have it, I think a connection may be required.
MY GTX 750Ti graphics card has been received by courier and unpacked looking undamaged.
But when placed in my PC the two fans rotate round and a red LED comes straight on before I actually turn on the main start up button on my computer?
My monitor says straight away no input when the pc is booted up on both HDM1 sockets. Also my ASUS A8N-SLI Deluxe motherboard comes up with an audio message of System Failed DVA test. The card does have the 6 pin power connecter socket but as I use my pc for normal and not gaming use it should still run ok on the PCI socket for power?
Have placed back my ASUS GeForce 6600GT graphics board all is well again. No problems at all running for the last 6-7 years with the ASUS motherboard. As this is a new board straight out of production there is nothing on the forums to see what problems are occurring with this graphics card let alone the ASUS website.
I am an electronics service engineer so the computer had been earthed and an electrostatic discharge wrist band bonded to earth. The power supply is 550 watts made by Corsair (no cheap PSU in this pc) before the graphics card was installed the old NVIDIA drivers and software was uninstalled first.
Spent hours checking the BIOS which again runs my old card and the same PCI slot was being used that the 6600GT runs on. The little booklet that came with the card is just about useless with no technical information at all. I have just about reached the end of trying to find the problem with this new graphics card and wished I had purchased an early model like the GTX660 that has been around for some time and plenty of information out there.
Any help on sorting this problem out would be gratefully received having been through the night until 2.30 am in the morning trying to see why I have a dud card and starting to pull what little hair is left out of my head. This is the first time I have installed a piece of hardware that has not run correctly from new. Used to service MAC units.
ASUS A8N-SLI Deluxe Motherboard.
ASUS GeForce 6600GT working graphics card.
AMD 64 3200+ processor which was to be upgraded to an Opteron 180 dual-core.
Windows 7 Home Edition.
Corsair TX550TM 550 watt psu.
This set up has been stable and before that running on Windows XP with no problems with my older graphics card.