Discussion in 'Reviews' started by crmaris, Mar 14, 2013.
To read this review go to: http://www.techpowerup.com/reviews/Enermax/ETA550AWT-M/
It looks that your sample haves broken RPM regulator :|
Unlikely. I believe that the main issue is that the minor rails' VRM circuits are heat-intolerant. This is probably why they underperformed at the dynamic load transients, and also why the fan has an aggressive speed curve.
They should've used more (powerful) MOSFETs for those, and added some more bulk capacity. Inductors are nice and beefy, no qualms there.
Overall, with some tweaking, this could've been a nice alternative to the Seasonic AM platform, or CWT's PUQ-B. However, as it stands now, it's not.
Ah nope. It is just that are rated/tuned for up to 40C and I test them at over 45C (because the higher the temp the tougher the tests). Nevertheless I also provide the full fan output noise profile at normal ambient, in order to show you the fan profile at more relaxed scenarios or in cases with very good airflow.
Actually I ran dymanic load tests at close to 40C temps and not at 45C. So I don't think that heat has to do so much with the dynamic loads response. It is just that the VRMs are weak or not optimal tuned (because the PWM controller also plays a significant part in transient loads).
Primary cap only rated for 85 °C? No wonder the warranty is short...
the main hold-up cap however is not the one that matters the most and in general doesn't take too much stress. On the contrary, the most important caps are the ones of the secondary side which take most burden. There 105C caps really make a difference.
This is true for decent PSUs with a good EMI/input filter, and especially APFC ones. In low-quality sub $25 PSUs, with inadequate or no input filtering, the primary caps are in actual danger of failing due to both internal overheating (for enduring high ripple/noise) and overvoltage (from occasional unfiltered voltage spikes).
While on the subject, it's actually just the voltage rating that's more important to primary caps in decent PSUs than temperature rating. The output voltage of the half-wave rectified AC is ~380V, but can occasionally hiccup to a bit higher due to various reasons which I won't go into right now. This is why I'd rather have 420V or even 450V-rated 85°C primary cap(s) than 400V-rated 105°C cap(s).
Thanks for your high informative post! Since most users are not familiar with electronics I chose not to mention the DC bus voltage of 380VDC and the tight regulation that a 400V APFC cap demands. However in some past reviews I highlighted this.
Also the main APFC cap isn't so stressed, at least from heat perspective, since it isn't blocked by other components and the unit's fan (usually top mounted) directly cools it, contrary to the secondary caps that usually are blocked by wires or other components.
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