(Redirected) Dell Precision 690 Graphics card upgrade, why the 512MB limit?

Hi there everyone,

So I am new to this forum thing so lets see where this goes. I've been given a Precision 690 work station. After a little tinkering and scratching my head, I've got it working on Windows 10. The crazy plan is to buy a few bits, like a pair of matched processors, up the RAM (I have the 1000W case) and throw in a modern graphics card. 

I know it is bit of an ancient beast now but the specifications state that is will only support graphics cards up to 512MB and no more than 150W power consumption. Given the new Nvidia GTX 10X0 series of cards are really low power consumption (1070 sub 150W) would these actually work or will the motherboard freak out because they have anywhere between 2-8GB or DDR5?

Any help would be much appreciated.