Few things have influenced product politics as much as 80 Plus Gold. Seasonic was the first manufacturer to list power supplies on its homepage meeting the EPRI (Electrical Power Research Institute) guidelines, and they presented their first certified models at CeBIT 2009. With the recently launched X-series, Seasonic aims to prove the marketability of 80 Plus Gold PSUs. We have the 750W model for review today, so let's see how it measures up. Is it a great new PSU, or is 80 Plus Gold simply a new way to increase prices?

Beyond the remarkable efficiency and high-quality technology, the power supply contains a fully modular cable system and makes a good impression with its simple elegance. The X-Series also includes "hybrid silent fan control", which regulates the three speed settings of the fan. The power supply runs completely silent up to 20% load, at which point the fan begins to rotate slowly; at higher loads fan speed increases again to enable sufficient cooling. Seasonic uses a PWM fan to allow graceful ramping up of fan speeds, which we will cover later in this review. Beyond the various certifications and features, this ATX 2.3 power supply offers a 5-year manufacturer warranty and uses active PFC to allow its use on all the major power grid standards.

Enermax delivered good results in our previous test with the latest Pro87+/Modu87+ series, and it will likely be Seasonic's main competition. Of particular note is that the noise levels of the Pro87+ and Modu87+ are extremely quiet throughout the load range. Enermax also delivers products catering to the midrange 500W market, but we will have to wait until summer for Seasonic's answer. When the other models are ready, Seasonic let us know that they will have PSUs rated below 500W for those that don't run a high-power system. We should also see additional manufacturers soon with their own 80 Plus Gold offerings, so it remains to be seen who will have the best product. Apart from the marketing hype, we'll need to see new features in order to surpass the competition.

The X-Series has an MSRP of $200 for the 750W unit we're reviewing, but you can find it online starting at $180. So let's see if this expensive power supply is worth the money and if Seasonic can achieve new efficiency levels. We will also look at the construction, voltage output, and the unusual topology; high efficiency isn't the only point of interest with the X-Series.

X750 - Product Contents and Overview
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  • MadMan007 - Wednesday, April 14, 2010 - link

    I hope they come out with some milder wattage units for those of use running 'normal' systems with a single GPU and maybe some non-ragged edge CPU and GPU overclocks. 83% efficiency at 10% of load is great.
  • 7Enigma - Wednesday, April 14, 2010 - link

    This was going to be my comment as well. I build average systems with the highest performance/$ so currently have a C2D with 4870 and will be looking in the next year to make the jump to quad cpu /5XXX gpu. With the fantastic idle consumption of both cpu and gpu the amount of time at or below that 20% level for this PSU is considerable.

    Give me the 500w version that is 85% @ 100w for <$125 and I'm sold.
  • jonup - Wednesday, April 14, 2010 - link

    Genuin question (not being surcastic):
    What is the big obsession with efficiency? 85% vs 87+%? Does it really matter?
    I use a OCZ's modular power supply and at full load (OCCT PSU) voltages remain stable, it's quite and I do not justify paying extra $100 for 3-5% efficiency. It's not like I am using $30 PSU. What am I missing?
  • Alexstarfire - Wednesday, April 14, 2010 - link

    Lower power bills. IF you maxed out a 750w then a 3% difference equates to at least 22.5w. Sounds like nothing, but if you leave your computer on 24/7 it adds up pretty fast. That's 540w per day so let's say 1Kw every 2 days. $.10, obviously this will vary the most since cost per Kw of electricity varies depending on location, every 2 days, that's roughly $18 per year.

    I doubt most would get anywhere near this, but expecting about $10 per year could be realistic depending on your computer specs and usage habits. So if you can get an extra 3-5% for less than $30-$40 then it's probably worth it. Though that's assuming the PSU lasts that long. If you can get more than 5% then it's probably almost always worth it. :P

    Lots of variables that really just depend on the individual. Very useful for someone like me that does a ton of gaming and video conversions.
  • LordanSS - Wednesday, April 14, 2010 - link

    Since we're on the topic of wattage and efficiency, I was wondering if I could get input from people about what "good", wattage would be for a PSU running a quad-core CPU (125W TDP, thereabouts), a 5970 (or wattage-equivalent video card combo) and 3 to 4 7200rpm mechanical HDDs?

    I was initially thinking about going with an 850w PSU, but if I can get "lower" with a big enough headroom for future component upgrades (like GPUs, that might consume more power), that'd be good.

    Thanks in advance.
  • sviola - Wednesday, December 29, 2010 - link

    Try using this tool:

  • ekerazha - Wednesday, April 14, 2010 - link

    On the contrary, the JonnyGURU review says the Seasonic X-Series performance are better than the Modu87+ series performance... who is wrong?
  • C'DaleRider - Wednesday, April 14, 2010 - link

    Given that AT always has spurious results in their load testing when compared to other reputable power supply testers, like at JonnyGuru, HardOCP, and Hardware Secrets, I'd tend to think AT still has yet to set up their Chroma properly.

    The aforementioned sites all showed a 1% voltage regulation on all rails yet AT has the 5V rail at 5%......inferior testing from AT. And when will AT learn those graphs are almost worthless? I'd really suggest going to JonnyGuru and look at charts with numbers, so you can see what the actual load being put on the power supply during testing and what stability the various rails demonstrated, along with actual captures from the oscilloscope of the ripple/noise generation and captures of the overshoot transient tracings.

    AT, while great at motherboard, cpu, and video card testing, is waaaay behind in power supply testing and while better than some sites, is almost becoming worthless in their results, esp. when compared to more reliable testers on the web.
  • ElBurroMaron - Wednesday, April 14, 2010 - link

    *lol* and what exactly makes you the expert? Just because you don't understand the graphs you conclude they're bad? And you think testing with a shoddy 3k Sunmoon is so much better than doing it with a 30k Chroma?

    I'd also love to see o-scope shots and a little more on loading scales but hey, maybe it'll still come one day. Maybe asking nicely and suggestion what could be added is better than posting such a stupid comment as yours?
  • MrSpadge - Wednesday, April 14, 2010 - link

    I got my Modu 87+ 500W for 110€ and it's just perfect for me.. I love it! Kind of.

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