I'm upgrading an HPE-570t desktop from 2011 with a GT-740 (  I first upgraded the PSU ( so that I'd have sufficient power for the new card.  The PSU upgrade went without issue, using the original video card. 
 
I installed the new card, and connected the prie power connector to the card.  On boot, it hung at the HP BIOS splash screen, and emitted a single beep.  Reverting to the old card allowed the system to boot fine.
 
The computer is running Windows 7 Home Premium 64 bit.  I am not sure what version of pci-express x16 the slot is, but I was under the impression that the 3.0 cards are backwards compatible with earlier version slots.

Welcome to the forums,
 

Basically, in mid 2011 the new video cards, starting from the 700 series to the new generation of 10 series come with an UEFI bios and they need a compatible motherboard/pc that supports UEFI. The older generation of video cards, anything from the 600 series and below, have a legacy bios which is fully supported with older motherboards/pc. The pcie generations 1,2,3 are all backwards compatible and you can definitely install a gen1 on a gen2/gen3 or gen2 on gen1/gen3, however, while gen3 is compatible with gen1 and gen2, it will most likely not work with older motherboards to due the UEFI bios.

Nevertheless, some manufacturers released a bios update for certain motherboards that would make them UEFI compatible. The best thing I can recommend is to update the bios of your motherboard. If your video card does not work after the update, it most likely won't work with your motherboard. 
 
You can also try following this guide >> http://support.hp.com/us-en/document/c03439317 which can help you in your current situation.
 

Yes,  is my computer, and I confirmed last night that I have the latest BIOS updates installed.  Sadly, the PC is 5 years old and there are no updates likely at this point, so I just need to find a compatible graphics card that would improve gaming over the Radeon 5570 HD that is currently in it.
 

GT 730 is pcie 2.0.  
 
Are there any settings on these cards that might help?

Would the GT 730 (pcie 2.0) be more likely to be compatible with my desktop than the GT 740 (pcie 3.0)?  

You can also grab a decent motherboard these days that's compatible with new/newer cards and are very reasonably priced too that you can use your CPU and RAM in starting at around 70 bones or so for an entry level mobo..Here are the specs for an HP Pavilion Elite HPE-580t (I think is what you have)..Check around with EVGA, ASUS, MSI, ASRock if you're inclined to replace the mobo with a better one..Not that hard to do.
 
Just a thought.

rjrizzuto57
Sorry for all the questions, but I want to make sure I'm not swapping parts endlessly.
 
- why is the 600 series compatible but the 700 series not?  Is the issue the pcie bus version, UEFI, or something else?  Why does UEFI matter if I'm running windows 7?
 
- Is it reasonable to look for a motherboard that is compatible with the 2nd gen i7 and the memory AND is compatible with the GT 740 I have?  Or would I be in the same incompatibility boat?
 
 Pretty soon all I'm salvaging is the sheetmetal.

The reason the 700 series isn't compatible with your motherboard is because the 700 series cards use a uefi vbios which your motherboard bios doesn't currently support. The 600 series and lower all use a regular vbios (legacy) which isn't uefi based. If you're dead set on using the 740 a motherboard upgrade would definitely help get it working.

Plus it may not be an upgrade over the 5570 that was in the pc to start.  I wanted faster and more video memory.
 

rjrizzuto57
I would love to hear from an EVGA representative about this.  The spec sheet for the 740 says it supports Windows XP and later, and makes no mention of such a requirement for a UEFI bios.  
 
Finding a 600 series may not be so easy...

GabrielS is a representative of EVGA. GabrielS responded to your thread on post #3.
 
Found a few users using this motherboard with a GT 740 without any issues. The board should work great with your 2nd gen i7. Just make sure you update the motherboard bios before installing the GT 740 if you decide to buy it.

The 740 would work just fine with a legacy vbios, however, evga has loaded all 700 series and newer series cards with uefi vbioses from the factory. Some cards like this one come with a hybird vbios swtich that allows you to change the card from uefi vbios to legacy vbios at will.

rjrizzuto57
Interesting.  I definitely learned something.  

The GPU worked up till the BIOS splash screen.  Please next time provide more accurate information so that the consumer can make an informed decision.  
 
Based on your updated information, do I now need to still worry that the GTX 650 I ordered will also not work in my system?  
 

I just signed up, because I found this thread through a Google search. I have a GT 740 ‘related’ question, for an old machine and I have no idea where to start here.

Posted. Thank you for pointing me in the right direction.