Welcome to the Forums xxcfdrr
 
MB: 132-CK-NF78-nForce 780i SLI 775 HP version or 132-YW-E178-nForce 780i SLI FTW version
 
Budget ?
 
plan on gaming ? what settings
 
what connections / cables do your monitors support
 
Your MB supports PCIe x16 speed is it ver   2.0 or 3.0    ?
 
What BIOS version you running in your MB / is it the newest ?

The cheapest 10 series card is the 1050, ~$110. E.g.: https://www.newegg.com/Product/Product.aspx?Item=N82E16814487295
 
That has 1 DVI, 1 HDMI, 1 DP, so if you are comfortable running the monitors with each different cables that would work. Otherwise I'd look for a used GTX 960, most of those have 3 DP, 1 DVI, 1 HDMI, and can be had for $80-$100 used.
 
Those should get you playback of the 4k video just fine, if you are wanting to edit or transcode the video you'll probably want to update the rest of the system.

I'd ask EVGA pre-Sales
 
Some older MB do not play well with the newer graphics boards, during POST there is a communication issue
 
 
https://www.evga.com/about/contactus/
 
 
If they say the newest recommended GPU would be a 900 series, then the GTX 980 are very powerful and have 4 GB RAM
 

Update. I did contact evga support and was advised the 500/600 series graphics card was about all this MB would accept. So I found a evga GTX680 on eBay and installed it. 
 
There is no improvement in video playback at all. I either have another issue or playing a 4K video from this drone takes an entirely new computer. The files are .mov and I've tried the Quicktime player and VLC. Both chunk and play maybe 1 frame every three seconds. Windows Media player says can't play file at all.
 
I am using 3 displays (DP-DVI-DVI) and the desktop in Win7 is extended across all of them. Would this cause a performance issue? Is there a video benchmark I can run to see if the video card is performing properly?
 
Thanks!

You gotta overclock that cpu.... preferably up over 3.4ghz at least. Don't do it unless you have the proper cooling setup to do it though, meaning fans, case, cpu cooler, TIM etc... You would also be better served testing with just one monitor to at least get the basics straightened out. Do you have the power options in windows set on max power and in the NVidia control center global options? You would most likely be better off using one of the older gpu drivers that came out during the middle of that cards life cycle too. Nvidias new drivers are famously terrible with older card gens.

Sajin

xxcfdrr
Is there a video benchmark I can run to see if the video card is performing properly?
 
Thanks!

Try benchmark.

I tried this benchmark and it locks up after a minute or so. :(

You also might have problem somewhere else. Keep in mind that recordind 4k videos does require a very speedy sd card. From your description it might be the same problem I've experienced with my drone. I thought it was playback problem but it turned out to be a sd card. Make sure you have faster card.
https://www.sdcard.org/de.../overview/speed_class/
For 4k you will need the fastest card out there. ( Samsung would be my choice YMMV)
Before you get the whole new computer try this.
Good luck. Ghost.

I believe the 780i motherboard does not support UEFI Bios. Any GPU would need to be non-UEFI type or  have VGA-Legacy firmware or possibly Hybrid BIOS ability.
Also the next problem is Bottlenecking. 2 Core Duo / Quad 2 Core 45nm also older 65nm cpu's (example - Intel E8500 / Intel Quad Extreme 2 Core QX9650) are not suitable to run high end GPU's made after 2013.
Therefore, 4K playback should not work at all.   At least you are able to connect 3 monitors with your current setup : )
 
* to quote what biscuit1 said  -" The 700 series cards will work on that motherboard . I have a 760 2gb version on my Win 10 / 7 dual boot 780 sli motherboard . Finally got Win 10 to behave by doing the reset option . Even a clean install wouldn't help .  But I also tested a 4k video on it I downloaded & converted it with the VLC player to a MP4 file . It would always flash to a pink screen on full screen playback in the VLC player . Later figured out that if I use Windows Media player it would play just fine in full screen . I also have a Q9550 o/c to 3.4 in it w/8gb of ram . With only a 20m down on dsl 4k streaming is just a dream with the newer V9 codec . Big difference between the 30 & 60hz 4k videos ."
 
biscuit1 response could work for you but at the expense of getting the parts even though cheap or reasonable on eBay ... better off getting a new PC.
Sell your parts on eBay or donate your PC to someone who does not have one.
 
* I do not recommend using an LGA 771 Modified Xeon cpu to LGA 775.  I have a GA-EP45-UD3P and tried several. They are great to play with and Over Clock with however, the problem comes when using programs which errors will pop up. Don't use mock up / rewritten BIOS to flash as they often will damage your mobo.
Your LGA 775 motherboard is best suited to use recommended standard CPU's made for it.
Only people with high tech skills and plenty of money can play silly games. DELIDDED is fun !!