Seasonic Prime Fanless 700 W

[crmaris]

The Seasonic Prime Fanless 700 W certainly isn't cheap, priced at $265, but offers the unique capability of a completely noise-free operation thanks to a passive design. With over 93% efficiency, it is among the best we've ever seen, but there are also some issues.

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[cellar door]

Hey crmaris! What's your opinion on Seasonic Prime Gold vs Focus Platinum? Specifically the GX-750GD2 model, so the smaller chassis. Are there any advantages to going with the Prime Gold vs the Focus Platinum 750 watt? I know Prime has 150k MTBF vs 100K for the Focus series and 0.5% voltage regulation.

Also would the 850watt Prime GX-850GD with the larger chassis be a better choice over the 750watt model?

Cheers!

 

[efikkan]

I'm also curious to see comparisons between the Focus series and the Prime series, even though they are priced very differently. The Focus series have been my go-to PSUs for years, and I currently have 2 850W Platinum and 1 650W Gold in use. I have mine running the fans all the time, and they are so quiet that it shouldn't be a problem in normal use cases.

While the Prime series obviously have a better design with higher efficiency etc., I would like to know more about when these are justified over a "mid-range" PSU like a Focus, and for which use cases outside edge cases like lab environments where EMI etc. is super important.

In my experience many PSUs tend to go "bad" long before they fail, creating instability and damaging harddrives. This has led me to keep track of the age of mine, to replace them when they get to 5-6 years of use, even though warranties typically are 8-12 years on good PSUs.
I would be super interested in a "long term use" review, comparing e.g. 5 year old PSUs to their original measurements, to see if we can conclude when it's smart to replace them.

 

[AsRock]

I'm also curious to see comparisons between the Focus series and the Prime series, even though they are priced very differently. The Focus series have been my go-to PSUs for years, and I currently have 2 850W Platinum and 1 650W Gold in use. I have mine running the fans all the time, and they are so quiet that it shouldn't be a problem in normal use cases.

While the Prime series obviously have a better design with higher efficiency etc., I would like to know more about when these are justified over a "mid-range" PSU like a Focus, and for which use cases outside edge cases like lab environments where EMI etc. is super important.

In my experience many PSUs tend to go "bad" long before they fail, creating instability and damaging harddrives. This has led me to keep track of the age of mine, to replace them when they get to 5-6 years of use, even though warranties typically are 8-12 years on good PSUs.
I would be super interested in a "long term use" review, comparing e.g. 5 year old PSUs to their original measurements, to see if we can conclude when it's smart to replace them.

A good quality PSU should never damage any thing old or not, i have had 2 other Seasonics that failed but no damage to the system ( seasonic RMA is painless and fast ), Seasonic platinum were on sale a few weeks ago i got mine for $126 shipped.

 

[crmaris]

Hey crmaris! What's your opinion on Seasonic Prime Gold vs Focus Platinum? Specifically the GX-750GD2 model, so the smaller chassis. Are there any advantages to going with the Prime Gold vs the Focus Platinum 750 watt? I know Prime has 150k MTBF vs 100K for the Focus series and 0.5% voltage regulation.

Also would the 850watt Prime GX-850GD with the larger chassis be a better choice over the 750watt model?

Cheers!

I like more the Prime platform than the Focus. Better and more capable platform.

 

[mechtech]

Good review! Thanks

I don't know if Seasonic is doing a bait n switch lately like many other manufacturer's out there, or if it's just trying to use whatever components (good or not) that are available/in-stock.

I remember the Seasonic focus gold getting really good reviews way back in the day from the Oklahoma Wolf (Jonny Guru), having used a few 550W gold ones lately with one blowing a 15A breaker, I don't know if they have the same build quality/components as they did back then?

My next one I think I may go superflower, or something else.

 

[looniam]

maybe i haven't paid attention but this is the first seasonic unit in a long time i've seen that did not daisy chain the pci-e (6+2) connections.

would consider that a plus (+) these days.

 

[AsRock]

maybe i haven't paid attention but this is the first seasonic unit in a long time i've seen that did not daisy chain the pci-e (6+2) connections.

would consider that a plus (+) these days.

Mines the same, don't know which model they start that though. Maybe at least all the Titanium ones ?.

 

[cellar door]

I like more the Prime platform than the Focus. Better and more capable platform.

Thanks for replying! Your PSU reviews are legendary at this point

Do you know of the top of your head if the smaller chassis version are just beefed up Focus platform? The 850watt Gold Prime comes in the larger chassis while the 750watt and down are smaller dimension chassis. Thanks again!

 

[Space Lynx]

I had a suspicion Seasonic was going downhill a bit, this confirms it, thanks.

Corsair platinum or titanium is my future.

 

[InVasMani]

I'd likely consider the 600w Seasonic if my 400w passive Seasonic decides to quite, but it's been going steady for a decade so it should last another decade let's not jinx it.

 

[sparkyar]

Well... I know that aluminium is getting very expensive, but thats a lot less heatsink´s mass than I expected for a fanless 700w psu...

 

[Cryogenta]

I'm surprised that this unit performs so much worse than the Nightjar 700W. Looking inside my own Nightjar 700 it appears almost identical to the Prime fanless 700W.

 

[R-T-B]

I had a suspicion Seasonic was going downhill a bit, this confirms it, thanks.

Corsair platinum or titanium is my future.

This is still a pretty solid PSU, but given past Seasonic standards we are used to, it is quite underwhelming.

 

[Readlight]

How turning on computer under 0 C damages it?

 

[crmaris]

Thanks for replying! Your PSU reviews are legendary at this point

Do you know of the top of your head if the smaller chassis version are just beefed up Focus platform? The 850watt Gold Prime comes in the larger chassis while the 750watt and down are smaller dimension chassis. Thanks again!

In general, whatever has 140mm length, has a Focus platform. Prime platforms are larger. I haven't touched Gold Primes for years, so I am not sure about the platforms they use, the whole line. Need to have more Seasonic reviews at TPU

 

[Plextek]

Hello techpowerup team,

thanks for the detailed article. Please i need help. As a normal user i don't understand everything in the article and i got some questions.

Can you describe a real usage scenario which damages other components like graphics card? As i see in the review, this can only happen with one of these Turn-On Transient Tests. Does it matter if it's a lower power card like RTX 3060 or high power card like RTX 3090?

So is it better to avoid a PSU OFF to Full Load cycle? Which cycles are the concerning ones? Is it only the one where power is completely off like switch OFF/ON mode on the PSU? Or is the usual boot cycle from Power OFF to ON (switch on PSU is always on ON) into operating system aswell a problem? I wonder is it best to keep the Computer in Windows Standby mode all the time to stay safe?

Thanks for help. Best regards.

 

[crmaris]

Hi! Turn-on Transient tests can (also) lead to problems during the system's wake-up after a sleep mode. Lately, there is lots of discussion in particular about PassMark's corresponding tests and how several PSUs fail in this, after long hours of testing. The graphics card and the rest parts do matter of course, because they affect energy consumption.

In normal operation, you won't see any failures in short term, but still, you can have compatibility issues with some "picky" hardware, meaning no boot, and also in some cases the stress on parts will be high leading to a shorter life.

This doesn't have to do with a specific turn-on scenario. The best is for the PSU to meet the ATX spec's requirements, which clearly state that voltage must increase smoothly during turn-on without any drops.

 

[Assimilator]

Seasonic, WTF happened here? Terrible regulation (relative to your older models), transient response failures on 3.3V, massive undershoot on 12V during power-on... how is it possible to release a model that performs worse than ones that are three years older?

I had a suspicion Seasonic was going downhill a bit, this confirms it, thanks.

Corsair platinum or titanium is my future.

... don't those use Seasonic as the OEM?

 

[R-T-B]

... don't those use Seasonic as the OEM?

No. CWT or Flextronics.

Seasonic, WTF happened here? Terrible regulation (relative to your older models), transient response failures on 3.3V, massive undershoot on 12V during power-on... how is it possible to release a model that performs worse than ones that are three years older?


... don't those use Seasonic as the OEM?

I almost wonder if the sample is bad or something.

 

[Assimilator]

I almost wonder if the sample is bad or something.

Aris wrote that he tested 3 samples with the exact same results. :/

 

[efikkan]

Aris wrote that he tested 3 samples with the exact same results. :/

This deserves more investigation.
Are we still talking about Prime Fanless specifically, or various Seasonic models?

Back when I bought my two Focus PX-850s (late 2020), I had difficulties finding in-depth reviews of Seasonic's recently refreshed lineup. JonnyGuru was still up back then, but only had reviews of the models prior to the refresh.

 

[Plextek]

Hi! Turn-on Transient tests can (also) lead to problems during the system's wake-up after a sleep mode. Lately, there is lots of discussion in particular about PassMark's corresponding tests and how several PSUs fail in this, after long hours of testing. The graphics card and the rest parts do matter of course, because they affect energy consumption.

In normal operation, you won't see any failures in short term, but still, you can have compatibility issues with some "picky" hardware, meaning no boot, and also in some cases the stress on parts will be high leading to a shorter life.

This doesn't have to do with a specific turn-on scenario. The best is for the PSU to meet the ATX spec's requirements, which clearly state that voltage must increase smoothly during turn-on without any drops.

Thanks for information crmaris! Like efikkan i really want to know what seasonic's statement to this issue is in near future. And what other PSU's of seasonic you can recommend? I'm interested for example aswell in the Focus PX or GX 850W series. And is the 600W fanless version safe to use?

Best regards

 

[crmaris]

I haven't reviewed a Seasonic GX, PX in ages! Hope this changes, soon. I have only tested the OEM versions in EVGA, NZXT, DeepCool but there are some differences in them, especially in the EVGA version. 600W review, is next but for another media most likely.

This deserves more investigation.
Are we still talking about Prime Fanless specifically, or various Seasonic models?

Back when I bought my two Focus PX-850s (late 2020), I had difficulties finding in-depth reviews of Seasonic's recently refreshed lineup. JonnyGuru was still up back then, but only had reviews of the models prior to the refresh.

My last Seasonic review was last ages ago. I need to cover more of their products because it is a major OEM and a key player in the PSU market!

 

[efikkan]

I haven't reviewed a Seasonic GX, PX in ages! Hope this changes, soon. I have only tested the OEM versions in EVGA, NZXT, DeepCool but there are some differences in them, especially in the EVGA version. 600W review, is next but for another media most likely.

My last Seasonic review was last ages ago. I need to cover more of their products because it is a major OEM and a key player in the PSU market!

I think there is demand for more proper reviews of Seasonic, especially in this vaccum without any good recent reviews.
(And I'm not counting those YouTube videos where someone unboxes a PSU and tells what they "think" about it.)