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.

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Load Testing

For those of you that are curious as to some of the reasoning and equipment behind our PSU testing program here at HardOCP, we have put together a living document that shares a lot of the behind the scenes of the program. The testing we are conducting today is exactly as described in that document and will begin with a range of loads tested at 120v input including our torture test and then move on to the same set of tests at 100v input but without the torture test.

120v Load Testing Results Initial

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120v Load Testing Results After 10 Years of Service

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Test #1 is equal to approximately 25% of the rated capacity of the X-750 at 45C. This makes Test #1 equal to ~188W by loading the 12v rail to 13a, the 5v rail to 2a, the 3.3v rail to 1a, the +5vsb to 2a, and the -12v to 0.5a. The results of Test #1 see the 5v and 3.3v rails starting off within 0.02v and 0.03v respectively of where they did in our original testing. The 12v rail shows a similar variation as it is coming in lower by 0.04v compared to our previous evaluation. The efficiency has shed ~1.18% in the time between when we tested the X-750 originally and today as it comes in at 86.32%.

Test #2 is equal to approximately 50% of the rated capacity of the X-750 at 45C. This makes Test #2 equal to ~375W by loading the 12v rail to 27a, the 5v rail to 4a, the 3.3v rail to 2a, the +5vsb to 2a, and the -12v to 0.5a. Test #2 sees the 12v rail drop by 0.14v, the 5v rail drop by 0.05v, and 3.3v all drop by 0.03v compared to Test #1 in our retest. That makes today's changes 0.08v, 0.03v, and 0.01v greater on the 12v, 5v, and 3.3v rails than they were previously during testing. When we look at the efficiency, we see that the decline over the last 10 years is coming in at 89.45% which is ~0.62% below previous.

Test #3 is equal to approximately 75% of the rated capacity of the X-750 at 45C. This makes Test #3 equal to ~563W by loading the 12v rail to 42a, the 5v rail to 7a, the 3.3v rail to 5a, the +5vsb to 2a, and the -12v to 0.5a. In Test #3, we see the 12v rail drop by 0.08v, the 5v rail drop by 0.07v, and the 3.3v rail drop by 0.04 today compared to Test #2. Compared to our initial testing 10 years ago, the 12v change is the same but the 5v rail drops by an additional 0.03v and the 3.3v rail drops by an additional 0.01v. Once more, we see that the efficiency has declined from our initial test to our retest today (by ~2.13%) as it comes in at 87.61%.

Test #4 is equal to approximately 100% of the rated capacity of the X-750 at 45C. This makes Test #4 equal to ~750W by loading the 12v rail to 60a, the 5v rail to 2a, the 3.3v rail to 1a, the +5vsb to 2a, and the -12v to 0.5a. In the final regular test, the full load test, we see the greatest difference today in our 12v rail. In this test, the 12v rail drops 0.11v while the 5v rail sheds 0.06v and the 3.3v rail stays even with Test #3. Compared to what we saw in our original testing years ago, the 5v rail has dropped an additional 0.02v, the 3.3v rail has matched its 0.00v change compared to Test #3, and the 12v rail is seeing an additional 0.03v drop. The efficiency once more posts a steep decline, compared to our original testing as the difference is ~1.92%, as it is coming in at 85.73%.

Load Testing Summary

The results for the Seasonic X-750's today are the most interesting ones we have seen among the reevaluations we have done. Why? Well, unlike with the Cooler Master Real Power Pro 1000W or SilverStone Olympia 1000W we previously saw, the Seasonic X-750 actually PASSED our load testing. Not only did it PASS our load testing it did so at the full 45C! We didn’t have to lower the temperature or play with any other parameters in order to get this unit to pass. The Seasonic X-750 manages to flat out be the first unit to PASS testing both initially and after an extended time in service.

Now, that said, it was not giving us the exact same performance as what we saw initially. To start, the voltage regulation that we saw in our retest today was a bit different from ~10 years ago as the 12v rail dropped by 0.33v today versus 0.21v before, the 5v rail dropped by 0.08v versus 0.06v, and the 3.3v rail dropped by 0.07v versus 0.05v. None of those changes are large in absolute values (well, maybe the 12v change is); which is good. Hell, just PASSING this testing today is good in a relative sense since this is the first unit we have re-reviewed that was able to do that. So, even if those absolute values had just sucked so very hard today, this would still be a relative win. When we move over to the efficiency side of things, we see that in the retest today the X-750 has seen a decline in efficiency, as well, with changes that range from 0.62% to 1.13% below what we saw ~10 years ago. Those changes are probably one of the worst results we see today, and they are a good bit worse than what we saw with the Cooler Master unit we re-reviewed it back in 2018. Overall though, the most important thing is that the X-750 is still able to PASS our load tests after all of that time in service which is an accomplishment even if the performance has gotten a bit worse over the years. Let's move on now to the 100v tests and see what we have there.