Seasonic PRIME 850W Platinum PSU Review

1. Introduction2. Bundle & Cabling3. External4. Internal5. Methodology and Testing6. Closing Thoughts7. View All Pages

It has been only a few days since we had a new Seasonic power supply in our labs for analysis. We have already looked at their 1200W and 1000W PRIME Platinum models in recent weeks, and today we analyse the 850W model. These power supplies are pure modular by design and feature low noise high grade Fluid Dynamic Bearing (FDB) cooling fans.

At this point we have only good things to say about the new PRIME Platinum power supplies. If the 850 Watt supply holds true to form then Seasonic will have one of their most consistent releases in recent history. We don't expect anything dramatically different from this unit, but only after testing will we know.

Overclockers UK are already taking orders for the Seasonic PRIME 850W Platinum power supply – priced at £204.95 inc vat HERE. Yes, there is no arguing that these units are expensive, and this isn't even their highest specification 850 Watt model either. The PRIME Titanium 850 Watt costs £25 more, available at £229.99 inc vat HERE.

850W PRIME Platinum Specifications:

– Model name: SSR-850TD Active PFC F3
– 80 PLUS®: Platinum
– Form Factor: Intel ATX 12 V
– Dimensions: 170mm (L) x 150mm (W) x 86mm (H) +/-1 mm
– Fan Size: 135 mm
– Fan Control: Premium Hybrid Fan Control
– Fan Bearing: Fluid Dynamic Bearing
– Life Expectancy: 70,000 hours at 40 °C, 15 % – 65 % RH
– Modularity: Fully Modular
– Cable type: Flat black cables
– Operating Temperature: 0 – 50 °C
– Hold-up Time: Above 30 ms
– MTBF @ 25 °C, excl. fan: 150,000 hours
– AC Input: Full Range
– Protection: OPP, OVP, UVP, OCP, OTP, SCP
– Safety and EMC: cTUVus, TUV, CB, CCC, BSMI, EAC
– Environmental Compliance: Energy Star, RoHS, WEEE, ErP Lot 6, REACH

Review photography handled in house at KitGuru with a Leica S series medium format camera and S series prime lens. Please do not use any of the images within this review without express permission.

The PRIME box is very eye catching, but it is also very difficult to photograph due to the shiny, reflective surfaces.

The front of the box shows 7+3 years warranty, but its now 7+5 years warranty coverage. You can read about the 12 years warranty (HERE).

The rear of the box is clutter free, with a list of key specifications and a high resolution image of the power supply.

The power supply itself is protected inside a soft felt bag which is wedged between thick slabs of foam for shipping protection.

Seasonic fully load this box with a wealth of extras. You get a modular cable bag, resealable plastic wallet, regional specific power connector, two kinds of cable ties, a case badge, branded sticker, an installation guide, mounting screws and user manual.

The Seasonic power supply is a pure modular design. The cables are a mixture of sleeved (ATX, CPU and PCIe) and flat ribbon style (peripherals), for ease of routing.

There are a total of six 6+2 Pin PCIe connectors to support very high end Crossfire and SLi systems (1000w and 1200W units have eight of these connectors available). Seasonic also supply dual 4+4 Pin ATX12V/EPS12V connectors to deliver power to two high end processors. There are a total of 10 SATA connectors available via the 850 watt unit, the 1000w and 1200w units have 12.

We like the appearance of the PRIME power supplies, and they are finished to a high standard. The Platinum units do not have the same shiny silver grill that is showcased on the Titanium models, so they are easy enough to tell apart.

The large fan is hidden behind the black grill with the PRIME logo in the center. If you pay close attention you can see the ‘n' shaped black grill which can be easily removed to fit a shiny panel – for the Titanium units.

This side of the unit is home to the power socket, power switch and Hybrid fan switch.

This Hybrid mode allows the fan to be disabled completely when the unit drops to a specific temperature threshold. Seasonic claim the Hybrid Fanless mode works up to:

• Approximately 50 % (±5 %) of system load at 25 °C.
• Approximately 30 % (±5 %) of system load at 40 °C.

Exactly the same modular connector layout as the 1200 Watt and 1000 Watt units we reviewed in previous weeks. The main M/B connectors are indicated along the bottom of the panel – clearly labelled. The Peripheral/SATA/Molex connectors are visible in a bank of two and three along the top right side. On the other side are all the CPU and PCI-e connectors in a row of 1, 3 and 2 from top to bottom (6 in total).

Exactly the same modular connector layout as the 1000 Watt unit we reviewed last week.

Seasonic PRIME 850W Platinum Power Supply
DC Output	+3.3V	+5V	+12V	-12V	+5Vsb
Max Output	20A	20A	70A	0.3A	2.5A
Total Power	100W		840W	3.6W	12.5W
	850 Watts

This 850W  power supply can deliver 70A via the +12V rail. Plenty of power on hand for a powerful SLI and Crossfire configuration. The 1000W model can deliver 83A and the 1200W model 100A.

Seasonic are using a Hong Hua 135mm fan, Model number HA13525H12F-Z – the same model featured in the PRIME 1000W and 1200W Platinum supplies. This is a Fluid Dynamic Bearing Fan selected for low noise characteristics. Regular readers may recall that the Seasonic Snow Silent 750W unit shipped with a smaller 120mm fan from the same company so its a good move that Seasonic are adopting larger fans.

Larger fans of similar quality are able to push more air at the same speeds, likely often spinning slower to reduce noise emissions. This fan is rated at around 150,000 hours at 25c.

Below - a High Resolution Gallery of the internal layout of the Seasonic PRIME 850W Platinum

The build quality, like previous 1000W and 1200W units, is very high. Soldering quality is excellent and we see little heatsinks in key positions which help deal with heat. These units have all very high efficiency levels so there is really no need for a lot of heatsinks in the design.

Seasonic are using high grade 105c rated Japanese capacitors in both primary and secondary stages which is good to see – if expected at the asking price. The two primary capacitors are both rated 400v 330uF, for a total of 660uF. By comparison the Titanium PRIME 850W model we reviewed some time ago was massively over specified – fitted with a 650uF and 450uF capacitor for a total output capacity of 1100uF.

Japanese caps are filtered through the secondary stage as well, which is reassuring to see.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. We run at 35c in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test in a single +12V configuration.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
100W	0.95	3.35	0.93	5.04	6.03	12.04	0.50	5.01	0.20	-12.02
225W	1.70	3.34	1.70	5.04	12.38	12.04	1.00	5.01	0.20	-12.03
450W	3.00	3.34	3.05	5.03	32.24	12.03	1.50	5.00	0.30	-12.03
675W	4.07	3.33	4.05	5.01	49.00	12.02	2.00	5.00	0.30	-12.03
850W	5.00	3.34	5.23	5.03	65.59	12.01	2.50	5.00	0.50	-12.03

Load regulation is superb with all rails exhibiting very minor fluctuation under load.

Seasonic PRIME 850W Platinum 850W	Maximum Load
	932W

We managed to get the power supply to deliver 932W before it would shut down, delivering around 82W more than rated specifications.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
760W	1.0	3.35	1.0	5.04	60.0	12.00	0.2	-12.02	0.50	5.00
165W	15.0	3.32	18.0	5.02	2.0	12.04	0.2	-12.01	0.50	5.00

The power supply dealt with the demanding cross load test very well exhibiting little fluctuation. It was tasked with 60A on the +12V rail and it held at 12.00V. The other rails delivered excellent results also.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
100W	5	5	5	5
225W	5	5	15	5
450W	5	5	15	5
675W	5	5	20	10
850W	10	5	25	10

Noise suppression results are really impressive, hitting 10mV and 5mV on +3.3V and +5V rails respectively. The +12V rail peaks at 25mV under full load conditions. Great results really overall.

Efficiency (%)
100W	89.4
225W	91.7
450W	94.1
675W	92.3
850W	91.4

Efficiency is extremely impressive, peaking at just over 94 percent at 50 percent load. This drops to around 91.5 percent at full load.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the power supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
100W	<28.0
225W	<28.0
450W	30.7
675W	33.9
850W	35.6

The large fan spins relatively slowly under most load conditions, it is only in the last 200 watts of rated power output that it spins up and can be audible. It is a quiet 850 watt power supply and rates highly in regards to low levels of noise emission.

Temperature (c)
	Intake	Exhaust
100W	37	39
225W	38	41
450W	40	48
675W	45	53
850W	47	59

The high levels of efficiency of this unit help reduce expelled heat. At full load we measured a +12c variable.

Maximum load	Efficiency
932 watts	90.8

At 932 watts, the efficiency level measures 90.8%. Not a practical situation to be running 24/7, but worth noting.

The Seasonic PRIME 850W Platinum is another great power supply from the company and one that strengthens the new range of Platinum units. It performs at the highest level and exhibits no weaknesses. Technically it is difficult to find fault.

While we have already reviewed 1000 watt and 1200 watt units in the same range, an 850 watt power supply is going to get a lot more attention, due to the lower price point. Let's be honest, not many people really need a 1200 watt power supply anyway.

Seasonic don't skimp on quality and have yet again opted for high grade 105c rated Japanese capacitors throughout. They seem so assured of their own quality that they raised the warranty on their units from 10 years to 12 years. Anyone buying a new Seasonic power supply should feel pretty confident that they are fully covered.

While I could comment again on the better looking Titanium rated PRIME units, I do feel the Titanium 850 Watt unit offers better value for money. It is in fact the greatest challenger the 850W Platinum power supply faces. Let me explain.

The Seasonic PRIME 850W Platinum unit that we reviewed today is priced at £204.95 inc vat (HERE) – which is a lot of money. For an extra £25, you can get the 850W Titanium unit which is technically a better power supply, quieter, and with increased levels of efficiency. This is only part of the picture however.

I have been saying for some time that the Seasonic Titanium 850 Watt is one of the most over specified units on the market. It was able to actually deliver almost 1,100 watts under extended load – which is staggering. This is because someone in Seasonic decided to incorporate hugely over-specified capacitors in this particular unit, it could easily have been marketed as a 1000 watt supply (it is more powerful than most!). This particular Titanium 850W is equipped with a 650uF and a 450uF capacitor in the primary stage, delivering a total of 1100uF. By comparison, the PRIME 850W Platinum reviewed today is equipped with two 330uF capacitors for a total of 660uF. That is a huge difference in capacitor capacity.

In my opinion, if I was already spending over £200 on a power supply, the Titanium unit with all the technical benefits, power efficiency improvements and massively over-specified capacitors is well worth the £25 extra.

Buy the Seasonic PRIME 850W Platinum from Overclockers UK for £204.95 inc vat HERE. The incredible Seasonic Prime Titanium 850W is available from Overclockers UK for £229.99 inc vat HERE.

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Pros:

• 12 year warranty.
• technically proficient.
• quiet under load.
• fully modular.
• high quality cabling.
• 105c Japanese caps.
• excellent load regulation.

Cons:

• expensive.
• capacitors are much smaller than in the 850W Titanium PRIME unit.

KitGuru says: The Seasonic PRIME 850W Platinum is yet another great power supply with class leading 12 year warranty.

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