A good 650W PSU (and that beQuiet 650W is a decent one) is plenty big - assuming it is functioning properly.
Note that all PSU calculators pad the results, some more than others, because they never ever want to recommend an under-powered PSU. The eXtreme Outervision PSU is, by far, the most conservative because it is the most comprehensive and most flexible. So it never goes overboard in the padding of the results. However, I padded it even more by pushing CPU Utilization to 100%, show you have 4 sticks of RAM, added a Blu-Ray drive, stated you use the computer 16 per day and as seen
here, the recommended PSU size is 575W. So you have a nice 75W to spare.
Now before someone jumps in and says 75W is not very much, note when calculating PSU requirements, regardless if using a calculator or if you do your own research and calculate manually, it must be assumed that the CPU, GPU, RAM, motherboard, drives, fans and everything else are all maxing out power demands at the exact same point in time. That would be an extremely rare event in real world usage.
I think you should borrow another PSU from another computer, perhaps from a trusting friend or relative and swap that in there see what happens. If the second PSU resolves your issue, I say 750W is considerably more than you need. 850W is overkill and a waste of money unless you stumble on a discounted deal that is too good to pass up.
PS: Note the Seasonic PSU calc is an abbreviated version of Outer Visions. Is say, use the more comprehensive and flexible original version if you want the most accurate estimate.
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Wait a minute! Who's thread is this? DRDOOM started it.