Power Supply Seasonic S1P-651FCPN5 650W FlexATX

jeshikat

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Seasonic S1P-651FCPN5



The Seasonic S1P-651FCPN5 is a new unit they showed at Computex 2017. It is a semi-modular (!) 650W Platinum-rated 150mm FlexATX. It is due to release by the end of the year.

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Specifications
  • Dimensions: 150mm x 81.5mm x 40.5mm (L x W x D)
  • Rated wattage: 650W
  • Efficiency: 80 PLUS Platinum
  • Rails: +3.3V 20A | +5V 20A | +12V 53A | -12V 0.3A | +5Vsb 3A
  • Fan: 40mm x 20mm

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Load table



The Seasonic has a 30% higher max wattage than the previous SFF-favorite, the 500W FSP FSP500-50FSPT. Unlike the FSP however, there is just a single 12V rail that is rated for a max of 53A (636W).

500W was already enough though, so more importantly for consumer use is the presence of the -12V (negative) rail that the FSP lacks. The -12V is completely obsolete on modern hardware but despite that some motherboards won't POST without it anyway.

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Fan



When I asked the product manager for this PSU, he said that the fan controller is temperature-based and does NOT spool up to full speed as part of the power supply's power on test procedure like the FSP (very annoyingly) does.

The fan on the display unit is a 40x20mm Jamicon KF0420 series, almost certainly the KF0420B1S in the 2-wire variant since the PM said the fan is dual ball bearing and it matches the 0.13A visible on the sticker.

Since the S1P-651FCPN5 is still in development it's not guaranteed this is the fan production units will use. However, changing the fan seems minor but it would require re-certification, so since it's supposed to release by the end of the year I think it's reasonable to assume it'll be the same.

Edit: After inquiring with Seasonic about if they had any noise specs of temperature/RPM curves yet, they informed me that the production unit will likely use the Sanyo Denki (Seasonic's preferred fan vendor when reliability is criticial) 9GA0412P6G001:



So at 16,000 RPM this isn't looking too good for noise levels at max load, though there's still hope for relatively quiet operation at loads a typical SFF build would see.

Despite being a ball-bearing the fan in the FSP 500W is surprisingly acceptable in regards to noise at loads up to about 150W. At 300W load on the FSP I was seeing 8600 RPM and at full load the fan was going full speed at 13k.

The fan in the Seasonic here by comparison maxes out at 8500 RPM, which combined with the temperature-based controller will hopefully mean a relatively quiet fan curve for the wattages most SFF builds will see.

Regardless, this wouldn't be SFF Forum if we didn't try to improve things, and luckily the fan is 20mm thick so there are some potential fan swap options to avoid that grinding noise inherent to ball bearings:
Both of these are available from industrial parts supplies like Mouser and should theoretically be drop-in replacements if the starting voltages aren't too far off.

Let me know if any of you find other options. Avoid just plain sleeve bearings though because at these RPMs they'll fail quickly. Also fan manufacturer specs are definitely better in the industrial side of things, but still suspect. Tread with caution.

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Cables



The S1P-651FCPN5 (or at least the demo unit at Computex) is semi-modular. The way it's implemented isn't anything special but it's better than nothing. The only sticking point is that the harness shown here only has 3x 12V wires which isn't really enough for both the CPU and PCIe connectors with a decently beefy rig.

I'd assume the harness could be modified but I have no idea what the MOQ is for that.

---------------------------​

Unlike many of the other FlexATX units I saw at Computex, since this is Seasonic there's a decent chance these will be available such that mere mortals can buy them.

I'll be sure to update this thread as new information comes in.
 
Last edited:

iFreilicht

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Feb 28, 2015
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Don't be so sure, I briefly had my hands on the 220mm 850W Platinum-rated FSP and after just a few minutes of a little less than 300W load in open air the fan went full speed. Then it even took several minutes after stopping the load for the fan to slow down.

So what sounds easily quiet on paper may not be :\

I really hope Seasonic can prove you wrong. Let's see where this goes.
 

jeshikat

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Since the S1P-651FCPN5 is still in development it's not guaranteed this is the fan production units will use.

I really hope Seasonic can prove you wrong. Let's see where this goes.

Whelp, looks like a max of 8600 RPM compared to the FSP 500W's 13,000 RPM despite cramming 30% more wattage into the same space was too good to be true. I asked Seasonic if they had any noise specs yet and they don't, but they told me this is the fan they'll likely use for production:

 
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jeshikat

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True, but 8600 RPM max and being able to drop-in fans with either the Sintec or Mag-Lev bearings would have been amazing.
 

jeshikat

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Luckily the 450W and 550W versions of this will use a fan with a lower max RPM. Seasonic is still investigating which fan they want to use on those two so I let them know we would like to see an emphasis on low noise.

Hopefully something comes of it and we'll finally have the FlexATX unit we've been dreaming of :)
 
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darksidecookie

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Feb 1, 2016
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might me a stupid question, but would the 650w be enough for dual 1080ti mini's, 140w cpu and an m.2 ssd?

if not what would be the bottleneck?
 

MarcParis

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Apr 1, 2016
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Seasonic is a mystery for me...they are developping real nice pro psu...and forget completely competitive sfx...i guess they prefer staying on pro market..:)

Anyway it's a promising psu...for your next gen cerberus @Aibohphobia ?..:)
 

jeshikat

Jessica. Wayward SFF.n Founder
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might me a stupid question, but would the 650w be enough for dual 1080ti mini's, 140w cpu and an m.2 ssd?

Not at stock clocks with everything at full load because the reference GTX 1080 Ti draws 267W at full load. So two of those and you only have 102W (on the 12V) left for the CPU and other parts. With underclocking of both the CPU and GPUs it's maybe doable.

I still wouldn't recommend it though unless you just don't care about noise.

Seasonic is a mystery for me...they are developping real nice pro psu...and forget completely competitive sfx

I don't think there's much overlap between the consumer and industrial sides of Seasonic, so it doesn't surprise me. If they still don't have a high-end consumer SFX platform within two years though I'll be extremely surprised since practically every other major OEM does at this point.

Anyway it's a promising psu...for your next gen cerberus?

It'd be for the Jolokia successor.
 

jeshikat

Jessica. Wayward SFF.n Founder
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No promises, but Seasonic is taking my feedback on noise under consideration :D
 

jeshikat

Jessica. Wayward SFF.n Founder
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I thought so too until I got a FSP FSP500-50FSPT, which is actually pretty quiet at idle and reasonable up to about 200W load. Past that it gets fairly loud at 350W and then really obnoxious at full load though.

So I think getting something acceptably quiet at 300W-350W load is achievable.
 

a_zhn

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Sep 28, 2020
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Long time lurker, and I don't mean to necro this thread, but whatever happened to this psu? Searching online brings up next to nothing other than this post and another related Computex 2017 round-up post. With the new RTX 3000 series power requirements, I'm looking for a flex-atx psu that's at least >600W to even remotely have a chance of sustaining a 3080.
 

ignsvn

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Long time lurker, and I don't mean to necro this thread, but whatever happened to this psu? Searching online brings up next to nothing other than this post and another related Computex 2017 round-up post. With the new RTX 3000 series power requirements, I'm looking for a flex-atx psu that's at least >600W to even remotely have a chance of sustaining a 3080.

Unfortunately you need to look elsewhere.

It's very common for companies to hold or not to proceed with some products they display in tech shows.