fasyrt

Of course.
 
Navitas GPM-450S, GPM-550S and GPM-650S use the High Power Astro Lite (HPM) platform, like in first generation Rosewill Photon 550-750, or SilentiumPC Supremo M1.
 
Navitas GPM-650C, GPM-750C, GPM-850C use CWT PUQ-G, used in things like old Corsair HX750.
 
Navitas GPM-1000C uses CWT CSH V-G, which is also the "father" of the later platforms used in Corsair's RM1000 and upcoming (then) RMx/i and HXi series.
 
Navitas GPM-1250C, PPS-1350FC and PPS-1450FC were beasts which used CWT PUO, the highest CWT had to offer at the time, with full bridge topology with an LLC resonant converter and interleaved PFC.
 
 
Edit:
Oh, and I almost forgot the most important thing - those were the times where CWT still used the famous Green Tape technology, which enhanced performance for low cost by leveraging the tape's pigment particles' different resonating frequency to counter-balance the ripple induced in the LLC transformer by the Pulse-Frequency Modulation converter. Even in the non-LLC PUQ-G.

I'd get Straight Power 11 550W if you have quiet fans in your case, if you got crappy fans it won't make a difference, go for RM550x for longer warranty
i got Pure Power 11 with same exact(silent wings 3) fan, and it's inaudible even at max rpm as max rpm is set rly low, it's as quiet as my Noctua 120mm fans on 950-1000rpm

there's not really a major technical difference between them
 
heck, the whisper and rmx are even from the same oem
 
I'd just get whatever you prefer here

@fasyrt Üdv a fedélzeten. PHn mintha láttam volna a neved.. 
 
I would recommend the Whisper M 550watt version. Though there are better units, but those generally cost more. 
 
To my knowledge, Whisper series are the cheapest full modular tier A+ PSUs. Though no shop or retailer provides the full seven years manufacturer warranty. 
 
When you're open for other options, corsair RMX or even TXM series PSUs are with full length manufacturers warranty time and free shipping from alza.hu .
 
I still believe, the whisper is a great choice. Generally, BF PSUs have best prices on Oazis. 
 
550 watts should be enough. Though custom 5700xt cards and 3700x with PBO can be hungry hardwares. 
 
Btw, please forget the 3800x. Total waste of money. Same / marginally better performance comparable to 3700x . But higher power consumption and way overpriced. Get 3700x and a good cooler, ie Alpenfohn Brocken3 or Scythe Mugen5.