What would you recommend? CX650 or RM550? I know CX is lower quality but higher wattage for this power-hungry machine (400W), but the RM550 is higher quality, much longer warranty. I'm just afraid that it would be under constant load if it's "only" 150W above the wattage of my PC. Or that's not true? It's just that in my head I always think that if you provide higher rated PSU it would work less thus survive longer
I would recommend either the RMx (better than the RM) 550w or EVGA G3 550w. I don't see how a 650 would be required here although it wouldn't hurt. Better to go with quality than more wattage once you meet the minimums. The CX is better than it use to be (like a lot) but it still is worth skipping eating out for a couple weeks and saving the extra 20 bucks for something better.
R9 290 is recommended a 650w because of power spikes. It'll run on a good 550w without issue otherwise. You are looking at a gpu well capable of a 325w usage, 100 for cpu and 100w for everything else, so 550w is squeezing by just under limits with maximum pc usage. You'd only be looking at a realistic usage of closer to 70% of maximum possible draw, so @ 400w ish continual.
However, it's also known that the R9 290 can hit spikes of upto 360w+ at times, out of the blue, totally unpredictable, which can and will trip the protective circuitry of lower wattage psus like a 550w, especially the better psus which generally try to maintain OPP of @ 120% (ATX standard).
While the RMx is a much better quality psu than any of the C series of any design or age, it's also both 100w lesser and has better protective circuitry. So you'd be happily gaming and out of nowhere pc shuts off. The CX650 would be the better choice overall.
This is only one game, with that gpu, others can be more or less demanding, stress tests like Firestrike can possibly see higher.
I'm buying it from Amazon and returning it back in case it's DOA would cost me plenty, so which one of the 2 is likely to come alive and in better shape. and which one is less prone to die suddenly on me? And also important is which one of the two is more quiet? Thanks! OR, you have a completely different suggestion for a different brand PSU that's quiet?
CX is slightly better than CXM. With any decent psu the chances of DOA are slim, the better the quality, the lower the chances. There are better options at Amazon but they cost more, Thermaltake Toughpower Grand, Antec Gold, Corsair RM, Seasonic Focus, Corsair TXM etc, but they are in the $85-$99 range. I'd love to see you go with better quality, better protections, better warranty, but it's not my money to spend.
If it wasn't for the spikes I'd be happier saying jump on the RM 550w, but that's a gamble, your pc will be running 150w heavy gaming, add in 350w worth of spikes and you could easily be seeing 500+w semi continual usage. The RM is easily built to handle that kind of load and abuse, it's just a question of how much do you put faith in your gpu. It's older, used, not brand new, does it have slightly higher power needs to maintain clocks, the 1100MHz OC versions hit 364w spikes. In just that one game tested. Or it could be you never see over 300w and be perfectly good topping out at @ 450w, well within the RM 550w ability.
For me, I'd bite the bullet and get a better unit, or wait to see if I could get better locally, on sale, combo cpu/mobo etc to open up options in budget, save up the extra $20 somehow.
Is the CX relatively in the "OK quality and not arriving DOA" section?
**And in case I DO use the R9 290, you mentioned more protections, but I saw that the CX has all the necessary protections, including OCP and OTP unlike other units in the same price range (Even SeaSonic S12III did not put them from some reason), or there are some other stuff I'm missing?
S12-III is not a worthy successor to the venerable S12-II. Lot of ppl are unhappy with Seasonic about this.
Yes, the CX is well into the 'ok quality and not gonna arrive DOA' catagory, it's a very decent psu, but like anything man made, there is always a chance of failure. There are no guarantees, even with the best units.
If you aren't going to use the R9 290, but opt to save up for a better gpu, then that's different. Any decent 550w will do nicely, as the newer gpus do not have anywhere near the power draw of those old AMD Radeons. You can power a rtx2080 on 550w comfortably.
If just sticking to the Vega8 graphics alone, or with a smaller gpu such as a gtx1050ti/1060 (equitable to the R9 290, just a lot newer and far less power demanding)