Seasonic X-Series 750W: Potent for the Price
by Martin Kaffei on April 13, 2010 11:13 PM EST- Posted in
- Cases/Cooling/PSUs
- Seasonic
- PSUs
X750 - Resonant Topology
Steep square-wave impulses are the standard output of integrated circuit voltages, steered by a PWM-chip. While the DC-to-DC converter improves efficiency on the DC side, there are still some switching losses on the AC side. Depending on various influences like operating time during a cyclic duration, switching frequencies, voltage, and current the level of loss varies. In order to prevent this loss effect, you can use resonant switching discharge with a resonant circuit. In order to understand the procedure, we have to clarify the significance of the term resonance first. Resonance means an increase in amplitude of a signal induced by an external influence that has a frequency close to the natural frequency of a system. To negate resonance, the current is forced to run in the opposite direction and clamped to a low voltage level during transfer.
Doing this requires two switches; the first one produces one half of an oscillation while the second creates the other half in reverse, with the resulting output being very close to a sine oscillation. The moment voltage crosses its zero point, where the following current still affects within the minus range, transistors are switching. The procedure can be described with ZVS (Zero Voltage Switching) and also exists in a reverse variant with Zero Current Switching (ZCS). Since the two physical values in the formula of the switching losses at the transistor play a role, the power dissipation is reduced by their minimization. One can operate almost free of loss. Another advantage is that the smooth oscillations (softer transitions) also lower electromagnetic interference; this was a problem with classical topologies, commonly seen in the first 80 Plus Gold PSUs.
Seasonic uses a traditional PWM controller during low load (which results in higher ripple and noise) since the resonance converter isn't easy to run at a high efficiency level at such loads. The integration of a special companion chip is crucial for this assembly. However, Enermax also works with frequency modulation to get higher efficiencies on larger loads. Enermax calls their design a DHT, Dynamic Hybrid Transformer. Dynamic might be overstating things a bit, as they still use fixed frequencies in several stages; a constantly varying modulation would be fully dynamic but it may not be necessary or ideal.
Manufacturers can often reach 80 Plus Gold level with a DC-to-DC converter, and that's exactly what Seasonic and other manufacturers do. However, there is still the possibility of selecting faster switches with an H-bridge design to make improvements, which brings us back to the EMI problem caused by the hard switching. It is much simpler to realize this solution than to implement a completely new technology. As usual, there's a balancing act and manufacturers try to keep the specific details of their designs secret; how they achieve Gold certification can bring disadvantages in some cases.
Regardless, we should note that getting one of these "green", high efficiency PSUs isn't going to save the environment. There are lots of wastes and pollutants created during production, and if you're replacing an old PSU you're still contributing to the land fill. Additionally, it's difficult to save money in the long term as the purchase price is often very high. The true benefit of power supplies like the X-Series is found in the deeper details. For example, higher efficiency means lower PSU temperatures, which affects the ambient temperature and may result in a system that lasts longer with fewer problems.
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Londeninfo - Wednesday, September 7, 2011 - link
My pc psu have been causing troubling me from many days. Whenever I touch the CPU i feel the electric shock.I cant figure out the problem!!!!<a href="http://www.londeninfo.com/">Londen</a&g...
Londeninfo - Wednesday, September 7, 2011 - link
<a href= "http://www.londeninfo.com" > Londen </a>Earthmonger - Wednesday, April 14, 2010 - link
Is it okay if I use this review to comment on something I'm getting really tired of seeing in upper class power supplies? It is? Thanks.[quote=Martin Kaffei]The cable sleeves are well done and help keep everything looking neat and organized, as does the fully modular cable system.[/quote]
This. These cables are not well sleeved. Every time I see bare wires on these expensive new units I roll my eyes, and add $40 to the end cost, since I'll have to completely re-sleeve all cables. It's awesome (seriously) that they're going fully modular these days, but for the price premiums, you'd think they would care more about the details.
bigboxes - Wednesday, April 14, 2010 - link
How anal are you? If you must cover the last 1/4 inch of wires where they meet up with the connector why don't you just use some additional shrink tubing?Minion4Hire - Wednesday, April 14, 2010 - link
Yea, what's the big deal? To my understanding one of the reasons they don't sleeve them to the very ends is to allow greater flexibility and bends in the cable to help make installation easier, which can be especially useful in smaller chassis. The shrink tubing at the end of the sleeve isn't exactly flexible, and would and would "pad" the back of the connectors by several centimeters if they were butting up against it. Better for the cables? Potentially. But I'm willing to bet that the average person would find it to be that much more painful and annoying during installation.Earthmonger - Wednesday, April 14, 2010 - link
Quite anal, yes. If a wire isn't completely sleeved, it shouldn't be sleeved at all. It just feels half-assed.As for the reduction in flexibility, not all heatshrink is rigid. I have some laying around here that is soft and pliant. Nor does it take several centimeters of heatshrink to do the job.
I do prefer individually sleeved cables though. Wire clusters aren't flexible enough, whereas I can bend a flat double-row of individuals right around a 90 degree without issue.
7Enigma - Wednesday, April 14, 2010 - link
What a poor comment. The purpose of sleeving is for better air flow and easier access to components. The terminal ends are kept free for better connectivity.You can glitter up your case/components all you want to satisfy the anal inner-you, but for the rest of us, I think we find this more than acceptable sleeving.
bigboxes - Wednesday, April 14, 2010 - link
I know what you are talking about. I just find you are a tad unrealistic. If you want bling then maybe you're looking at the wrong mfg. Seasonic is for the enthusiast. It's fairly plain, but well built and engineered. I prefer function over form and I still think it looks good. Of course I don't have a window or lights in my case. I like quiet. I have sleeving mesh and shrink tubing, but the sleeving on this unit (and all Seasonic PSUs) is top notch. I have sleeved up to (and even over) the connector before. I just think you are asking too much from the mfg in this case. Sounds like you are going to redo whatever someone else does because you have certain tastes that only you can live up to. And that's tottally understandable. I'm sure most people think I'm too anal over my builds too. :)HOOfan 1 - Wednesday, April 14, 2010 - link
If I saw bare wires...I would stay very far away from the PSU...talk about short circuits....Luckily, these wires aren't bare, they are covered in plastic isulation.
Smartass remark out of the way, there is no way to extend the sleave all the way to the end, the wires would have to be individually sleaved, or done like the flexforce cables...individually sleaving them would raise the price exponentially.
MrSpadge - Wednesday, April 14, 2010 - link
What an amazing comment!(1) you need to spot the "missing" sleeve at the end of the cables
(2) you have to recognize it as something you don't like
(3) you have to seriously consider fixing it for 40$ in case you'd want to buy this PSU
I'm not sure anyone else on this planet could fulfill all 3 ;)