If you are planning in changing the system based for dual Xeon E5530 to dual Xeon E5 processors and using high end video graphics of course the performance will improve.
In regards with the Xeon PHI , you may want to access the following link. It will provided you a lot of information about it and it explains when the Xeon PHI is or not suitable for someone.
I don't know about 3DSMax, but I do know rendering software is either CPU driven or GPU driven.
In my case, I have Keyshot rendering which is entirely CPU based, that is the more cores\threads the better, as an example a 10 hour rendering on a 4 core, will take about 5 hours on 8 cores, 2.5 hours on 16 cores.
Having said that, there are rendering programs (contact 3DS MAX tech support and ask them if the program is GPU or CPU driven) that use the GPU for rendering, in that case, your better off investing in a dual\triple graphics solution. In my case, Keyshot, for example, there is NO Performance gain by using a high-end graphics card, (not that it hurts to have one) it's all about the cores\threads, the more the better, the faster the better, what can you afford, and again, where is the money better spent, CPU(s) or GPU(s)?
Another thing to keep in mind, is your system speed, my system will run at 1333, 1,600, 1,800MHz depending on what kind of RAM I use and what flavor of CPU. One can again gain +10% ~20% rendering performance by getting maximum speed RAM, 32+ GB is not bad either, especially as your core\thread count goes up.
For rendering, this is just my opinion, for a dual CPU Workstation rendering program that is CPU driven, I'd recommend either\or the new 10\12 core v2 E5-26XXCPUs' and 32GB of RAM per processor for starters.
If it's GPU driven, I'd give the W7000 cards a look. Like I said, this is based on my limited rendering experience with one program. As they say, "Your mileage may vary"!