I am running a Gigabyte P55A-UD3,
Device name Johns-PC
Processor Intel(R) Xeon(R) CPU X3470 @ 2.93GHz 1.33 GHz
Installed RAM 16.0 GB
Device ID 62DBF3A6-9478-4DE7-9324-BBDADBE6D1E3
Product ID 00330-80000-00000-AA326
System type 64-bit operating system, x64-based processor
Pen and touch No pen or touch input is available for this display
Video Card Benchmarks - Over 1,000,000 Video Cards and 3,900 Models Benchmarked and compared in graph form - This page contains a graph which includes benchmark results for high end Video Cards - such as recently released ATI and nVidia video cards using the PCI-Express standard.
Every card listed in the high_end_gpus page performs better than the GT 740.
This link will help you with a second opinion comparison.
If you don't have 500+ watts PSU. Your options will be limited to specific tiers within each generation of GPUs. For instance your card is a 7th gen x40 tier and uses upto 64 watts of power. The x40 is a low power GPU. Each tier increase uses even more power to operate. My card is a GTX 660. The 660 is a 6th gen x60 tier. My card is one generation older than yours, two tiers higher, and uses upto 140 watts of power.
I don't want to make the post too long. So I will stop here. If you need further explanation, I can continue.
What size power supply do you have?
Are you going to be gaming?
What is your budget?
Are you looking for a brand new card or will second hand work for you?