I'm about to purchase a New 27" iMac i7 4ghz, 16gb ram. 4gb or 2gb Video Card?

New 27 " iMac i7 4ghz, 16gb ram
Magic Trackpad 2
Purpose:
Photo editing using PScc and Lightroom CC
Some Video editing with Premier Pro, probably from a yet to be purchased iPhone 6s + 64gb

Which Video Card, 4gb or 2gb do I want??? and WHY????

Thank you much for taking the time to respond.
PhilR

While I don't do any type of photo or video editing myself, I checked the website for those programs you listed and they recommended 2gb of vram. Maybe someone with some actual hands on experience with those programs can chime in.

Thank you much for your quick response.

Upgrade the memory from STOCK 8GB to your 16GB after your purchase for far less than half the cost Apple is charging (takes a brief minute to do easily) and that gives you the money to go from 2GB to 4GB on the 395X card at no additional cost.

Excellent idea..........but..........what are the specs on the memory? I called G.Skill and they were not sure. I called Apple Corporate and got hung-up on. I called my local Apple Store in Boca Raton, FL and spoke to a Tech that tried his hardest to find the specs.
We came up with the following:
Memory

8GB (two 4GB) of 1867MHz DDR3 memory; four SO-DIMM slots, user accessible
Configurable to 16GB or 32GB

G.Skill came up with: 4 - 8gb F3-1866V11Q-32GRSL

If I could confirm this, I would order the iMac w/8gb and replace the memory. Do we need 'ECC' mem...no one seems to know. The local store does not have a New iMac in stock to review........arghhhhhhhhhhhhhhhhhh
I want to place an order.

Also, what is the benefit of the 4gb Video card?

Many thanks,
Phil

I would go for the 4GB if those applications recommend 2. Just to be sure. You wouldn't need to upgrade your computer for a while as well.

You don't need ECC memory. i7 processors don't support ECC memory.

The stock iMac ships with 2x4GB sticks. Since there are 4 slots, you can just buy another 2 sticks to have 4x4GB = 16 GB.

You can search newegg or ask G-skill about F3-1866C11D-8GRSL (I would give you a link, but iMore forum says I need to have 10 posts to give you a link.)

Thank you, I did speak to G.Skill yesterday. They recommended the following: F3-1866C11Q-32GRSL.
I've decided to go for 32gb. The problem is, the tech was not 100% sure if this will work. He recommended purchasing from NewEgg. However, NewEgg appears to charge a 15% restocking fee.
Should we consider Buffered or Non-buffered memory.........this seems to be more difficult than it needs to be...........

Have you checked Crucial for memory?

Crucial is a good option. https://forums.imore.com/e?link=http...token=flsup9AV is another place to try. I've had a good experience getting RAM upgrades from them.
iMac Memory Upgrades Up to 32GB From OWC

Your are probably okay with 2GB GPU. You will likely see more performance gains in Premiere Pro than PS or LR, but unless you are really pushing things I don't think you need the 4GB.