Seasonic X-750 750W PSU 10 Year Redux

One of our readers' favorite PSU topics has been when we look back at a previously reviewed PSU that has been in service for a long while, and whether or not that PSU will still meet ATX spec and handle its previously rated wattage load. Today we have a Seasonic PSU that has been in service for a decade.



Today, we have a bit of a different kind of "review" in that this is not the first time we have seen the Seasonic X-750. Rather, this unit was first reviewed about 10 years ago and earned a Gold award at that time. In that time, this product has, obviously, been discontinued and surpassed due to new product development and the general progression of electronics as we know it. However, this unit formed the basis for many developments and platform characteristics that Seasonic has carried forward to this day. Additionally, enthusiasts often make use of certain parts of builds over and over again (or we may setup a system for a family member and simply let it go for years on end) with power supplies often being one of those products people don’t think about upgrading, or replacing, as often as other components. That has often lead to questions from readers about, "What happens to a power supply that has been in use for an extended period of time?" We have previous looked at this twice before and the results were interesting in that those units no longer could perform to their full rated capacity. Today, we have an opportunity to look at that question a third time as we revisit the Seasonic X-750 that we first reviewed back in 2009. After tearing down the system that this unit was in, and putting this unit back on the load tester, we get to see what 10 years of office/gaming PC usage has done to this unit and to see if, maybe, this unit can buck that trend of not being capable of delivering rated capacity that we have seen from our two previous examples. So, let's see how this went!

HardOCP’s testing methodology is intended to very much push power supplies to their advertised wattage rating in temperatures that will represent some of the hottest computer enthusiast cases. So if a unit passes all our testing it is definitely not something to take lightly. In fact we expect more power supplies to fail our testing than make it through unscathed.

Load Testing

The load testing results for the Seasonic X-750 paint a picture that differs from what we have seen from previous rereviews but, at the same time, make sense. The results we see today differ in that this unit PASSED all of our tests today which neither the SilverStone Olympia 1000W or Cooler Master Real Power Pro 1000W that we previously looked at were able to do. That is impressive. Now, there is a bit of a caveat to that and that caveat is this. While this unit did pass all of our tests, it did not do as well as it did ~10 years ago (the voltage regulation was a bit looser than what we saw initially on the 12v, 5v, and 3.3v rails). But, let’s be honest. That makes sense. Time and workload take a toll on everything so, some amount of, change is to be expected. How much change though is going to be highly variable and we can’t say if the changes we see today would be typical or not. They simply are what we have observed from our single sample running our single hardware configuration for the last ~10 years. Even with this wear and tear, our unit was well within the ATX12v/EPS specification limits and it did do fine compared to many power supplies we have seen over the years of similar capacity even if it does not meet its own previous metrics. Now, when we look at the efficiency numbers, we see that the efficiency has also suffered over the years as the 120v differences ranged from ~0.62% to 2.13% and the 100v differences ranged from ~0.83% to ~3.57%. Obviously, this means that the 100v efficiency has suffered a bit more than the 120v which is probably to be expected at this point as we have seen this same outcome with both previous rereviews as well.

DC Output Quality

When we look at the DC Output Quality of this unit, we see that it did a very good job today and we did not see the kinds of changes we saw in our load tests. Indeed, the DC Output Quality of this unit is roughly equivalent to what we saw ~10 years ago. Sure, during testing, we did see some numbers that varied from previous tests if we compare Test to Test. However, when we do that the peak difference is just ~10mV. When we look at peak values overall, these differences shrink to ~5mV. On top of that, the closest that any of the rails came to the ATX12v specification limit was the 5v rail which hit 25mV when the limit is 50mV. The 12v rail hit the same ~35mV that it did ~10 years ago and the 3.3v rail did better today as it peaked at ~15mV of ripple/noise. Now, while it is conceivable that these values could get worse if this unit were to be put back in a system after today, it seems that this unit has aged remarkably well in this aspect of testing over the years.


In our retest today, the Seasonic X-750 never seemed to be noisy and that is largely true of this unit over the last ~10 years. This unit has been just fine on the desktop day in and day out. Unlike previous units we re-reviewed, the fan does not SEEM to have aged and it SEEMS to be as quiet as the day it went into the system. Now, obviously, that is not technically possible, but the point is the changes in its performance over the years have been minor. While the double ball bearing fan that this unit is equipped with is not the most favored thing among quiet cooling enthusiasts it was perfectly serviceable over the last ten years. Also, unlike some of the "quieter" fan types, like sleeve bearing fans, this fan bearing type is generally more robust. Given that this particular example lived 10 years with no APPARENT change in its noise or performance profile this would seem to, anecdotally, support this in a qualitative manner. Overall, the performance of this unit in this regard seems to have held with what we experienced during its load testing ~10 years ago.

Paul's Thoughts:

Today, we had the opportunity to look back at the Seasonic X-750 a second time, much like we did with the SilverStone Olympia 1000W and Cooler Master Real Power Pro 1000W. The funny thing is none of these pieces were intended to exist, but through a confluence of factors we have been fortunate enough to write these pieces for you and they have all turned out to be, I think, interesting. So here we are again, one final time, today looking at a unit that I plucked out of the review pile years ago to be used daily in the system sitting right next to me on my desk. In that regard, this unit has slaved away for ~10 years pounding out the more than 300 power supply articles we have published here at [H]ardOCP with just regular visits from ye olde canned air.

The caveats we noted the last two time should be observed again today. It is interesting to look at what has happened to one particular unit over time, however this observation is not of a completely controlled design (it is closer to controlled than the last time since this unit never changed systems) and it produces only an observation not scientifically rigorous data as we explained before. I would also say that there is no way to say if this unit has experienced a representative form of "normal" usage or not as this system started off as top of the line system but after ~10 years it is, well, not.

That all said, this unit did GREAT. I have ZERO complaints about this unit after the last ~10 years and this design is a real workhorse that Seasonic has used, modified, and developed over the years into some truly excellent products. When Seasonic introduced this design, it was a significant departure from what they, and most everyone else, was doing in the enthusiast market. New things are often fraught with growing pains, problems, or acceptance issues. However, in the time since this unit was introduced, we have seen Seasonic grow from a solid OEM provider that had almost zero presence in the enthusiast market to one of the most successful and well-established brands in power supplies with successful product after successful product after successful product. This growth was largely kick started by the X-Series units so Seasonic owes an awful lot to this little design. At that time, these units certainly did seem like they were quality units but now, ~10 years later, that legacy seems to be firmly established. So, if when I said "buy the best quality power supply you can buy" previously you took that to mean buy one of these original X-750’s it looks like you made a good choice. You ponied up for the quality unit, and you got the quality result.

[H]ardOCP Seasonic X-750 review unit, Born 2009 - Deceased TBD.

The Bottom Line

Today, we have had the opportunity to look back at one of the first truly modern power supplies that we reviewed after ~10 years of service with the Seasonic X-750. While this example of that product has seen some changes in performance over the years it has been in service (the voltage regulation has become looser and the efficacy has dropped), this unit has done something neither of the previous units we have re-reviewed were able to do; complete testing in specification. In those previous examples, we observed the intuitive assumption that use, and time, will result in a loss of performance of a product.

Today, we were expecting the same. However, while what we saw was in the same vein it was not to the same extent. Yes, the Seasonic X-750 did see measurable performance degradation after ~10 years of use. However, unlike those previous examples this unit was still within specifications. Beyond that, if we were to turn back the hands of time to 2009, and saw these same values when reviewing this unit then, these would still be favorable numbers. Overall then, among the three products we have had the opportunity to re-review, the Seasonic X-750 has to stand out as the best quality unit we have seen over the long haul. Certainly, there may be better units out there from Seasonic or other vendors but among the ones we can point to numbers for, this unit takes the cake.

That all said, it looks like this unit is very fitting to be what we are looking at today for another reason. This was a unit we reviewed here at HardOCP very early on when we started reviewing power supplies and it will be one of, or the, last reviews we publish here at HardOCP. A sort of bookends if you will. With that being the case, I would like to say "Thank You" to all of the readers out there who have been reading these reviews over the last 12 years and 1 month. While HardOCP is being mothballed, the HardForum live on as long as you guys, our readers, make it so. I’ll catch you guys there. From the front page though, I bid you; adieu.