|To answer your question. There is no rule that a PSU can be too large a capacity. That said, over the years voltage requirements for the three main voltages supplied by a PSU have changed to utilize the +12V rail more and the +3.3V and +5V less. Your photo doesn't show which ATX version that PSU is. |
See the link below for an understanding of the progression of the ATX standards for PSUs.
Your current PSU specs show too much capacity on the 3.3V and 5V rails while the +12V is marginal.
The 850W PSU is overkill for almost all modern builds due to the the smaller die sizes in use today for CPU and GPU chips. A few years ago some high end Graphics cards pulled close to 200W by them selves and boards were designed to use two or three of these. AMD still has 125W/140W CPUs in production.
I suggest you install HWMonitor and see how your current PSU is performing at idle and under load. The 3.3, 5, and 12V rails should all read +- 5% of the stated values. If that is not what you are getting then you may want to swap it out at that point. This assumes the 2 units are the same form factor, which also part of the ATX standards.