dell dimension 8400 and GeForce GT 710

I agree with the above - but, the only potential hiccup is that sometimes older Dell systems, due to BIOS limitations, will refuse to play nicely with newer cards.

Definitely make sure you have the latest BIOS available for your system, but sometimes, OEMs simply limit what video cards their systems will work with.
 
Thanks, I thought that it may work. The 8400 has been a real workhorse for the last 13 years. I'm wondering about the BIOS though, The existing BIOS is A03 and the latest on the Dell site is A09. I'm always a little apprehensive about fiddling with the BIOS. Has anyone had any problems with updating the BIOS?
 
The Dell BIOS update utility works in Windows and I've never had an issue. It may update the PCIe spec. from 1.0 to 2.0 so I would do it. The manual says it supports GPUs up to 75W (and then says add a fan if going over that) The PSU is 350W so maybe there's a6 pin PCIe cable. I would suggest a GT730 1GB DDR5 instead. It's a much better card, and the 2GB memory (DDR3?) could be a problem. A- it's much slower than DDR5, and B- GPUs cache textures in memory adresses from the top down. Since you have 4GB memory capacity you can't afford 2GB going to this purpose. GPUs didn't have much RAM back then so it wasn;t an issue. a good 1GB card is the way to go. There are some 1GB GTX750s out there also.
Here are some builds with GTX480 in them whatever that means.
http://www.userbenchmark.com/System/Dell-Dimension-8400/6552
I did see one with an SSD there. Small ones are cheap. that will help alot if you run out of system meory. Turn off Auto defragmentation if you do that.
But the 710 shouldn't be a problem as long as it doesn't require a UEFI BIOS. If it's UEFI rated it won't work
GTX480 is above GTX750 on the GPU hierarchy chart.
http://www.tomshardware.com/reviews/gpu-hierarchy,4388.html
 
I bought the GT710 already. It was for another computer but it's PCIe X16 slot is limited to 35 watts. That's why I'm considering putting it in the 8400. I always hate sending something and taking a hit on the restocking charges. I'm going to try it in the 8400 tomorrow after I work up the energy to unhooking all the cables from the 8400.