ASRock Steel Legend SL-850G PSU Review

1. Introduction2. Bundle & Cabling3. External4. Internal5. Testing Methodology and Results6. Closing Thoughts7. View All Pages

Today we take a look at a new power supply from ASRock, the Steel Legend SL-850G. This fully modular unit has achieved Cybenetics Platinum ratings, is ATX 3.1 and PCIe 5.1 compliant and comes equipped with Japanese capacitors. ASRock offer a 10 year warranty to support this supply.

ASRock are releasing four units in this Steel Legend series, the SL-1000G, the SL-750G, and the SL-650G alongside the SL-850G unit we are reviewing today. ASRock are keen to point out that these units are very quiet in operation, having achieved the Cybenetics A+ rating.

SL-850G Overview:

• Wattage Range 1000W 850W 750W 650W
• 80 PLUS Efficiency Gold 90% 2% higher than Gold standard)
• Modular Fully Modular design
• Compact Dimension 150mm x 150mm x 86mm
• PCIe 5.1 Cable Dual Color, 105 Durable
• iCOOL Intelligent Fan Control Mode
• Global 10 Years Warranty

The SL-850G artwork is quite subdued but it lists a range of selling points on the front such as the 10 year warranty, noise rating, efficiency rating and ATX 3.1 / PCIe 5.1 compatibility.

The rear of the box highlights the cables, an efficiency chart and a list of features.

Inside the box, the power supply is sandwiched between two slabs of foam. The accessories are on the other side of the box.

ASRock supply a little leaflet on the power supply along with a regional specific cable and two kinds of cable tie.

ASRock are using thin ribbon style cables which can help with routing during a system build.

In the efforts to help end users be assured their cables are plugged in correctly, ASRock have coloured the connector parts green – as the diagram above shows, this ensures you can see if they are seated properly before turning on the system. A pretty neat idea, but we imagine most people may not even realise.

None of the cables have in cable capacitors which is good.

• Motherboard cable (24pin) – 1x
• EPS 12V CPU connectors (4+4pin) – 2x
• PCIe5.1 connectors(12+4pin) Dual Color – 1x
• PCIe connectors (6+2pin) – 3x
• 4-pin Peripheral connectors – 3x
• SATA 5-pin connectors – 9x

The ASRock Steel Legend SL-850G measures 150mm x 150mm x 86mm (L x W x H). The paint quality seems quite high with good quality across all the panels.

A large fan can be seen behind the grilled top of the unit – we will take a closer look at this shortly when we open it up.

The modular bay is split into four sections across two rows. All the ports are labelled for ease of use during the install phase.

The power side is home to a vented panel for airflow, with a power connector and switch on the left side. On the right side there is a switch labelled ‘iCool'. This switch when enabled will switch the fan off in lower demand situations. It works pretty much identically to all the other semi passive mode switches we have seen from brands such as Corsair, Seasonic and FSP.

This unit can deliver 70.9A to the main +12V rail. Both secondary +3.3V and +5V rails can deliver 20A for a total of 120W.

ASRock are using a high grade fluid dynamic bearing (FDB) fan – it's 135mm with model number S1352512EH-3M. FDB fans are really good and generally exhibit long life span and lower noise emissions.

As you can see by the images above, ASRock are using a small piece of plastic with perforated holes to specifically direct air flow over specific components underneath.

This power supply is an OEM partner design from HEC. The overall design is clean and soldering quality is pretty high throughout. They cheekily have branded their logo in green, it's immediately noticeable when you open the unit. Not that you should open this unit if you buy it as you will invalidate the 10 year warranty – that is why we are here after all! Just be aware that the Challenger branded units in the ASRock range – rated Gold and Bronze – only have a 5 year warranty so it is worth paying attention to this; not all ASRock power supplies are the same in that regard.

HEC/ASRock have adopted high grade Japanese capacitors throughout the design, with a high grade Japanese 105C-rated Nippon Chemi Con capacitor in the primary stage. This capacitor is rated 400V 560uF and it is from their KMR family. These capacitors have held up very well in our testing over the years.

The unit offers SCP, OPP, OCP, OTP, OVP and UVP protections.

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
85W	0.95	3.33	0.92	5.02	6.00	12.04	0.50	5.01	0.20	-12.00
170W	1.70	3.33	1.67	5.02	12.35	12.04	1.00	5.01	0.20	-12.01
425W	3.00	3.33	3.05	5.02	32.20	12.02	1.50	5.01	0.30	-12.01
640W	4.05	3.33	4.05	5.01	49.00	12.00	2.00	5.01	0.30	-12.00
850W	5.00	3.33	5.23	5.02	65.52	11.98	2.50	5.01	0.50	-12.01

Load regulation is really good on all the rails.

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	3.33	1.0	5.02	60.0	11.99	0.2	-12.01	0.50	5.01
165W	15.0	3.32	18.0	5.01	2.0	12.03	0.2	-12.01	0.50	5.01

The power supply dealt with the demanding cross load test without any major concerns.

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	13	13	20	13
225W	15	15	24	15
450W	16	16	31	17
675W	17	16	37	17
850W	19	17	46	18

Noise suppression is pretty good across the minor rails. The +12V rail peaks at around 45mV which is well within industry rated tolerances. Not the greatest we have seen in 2024, but perfectly acceptable.

Efficiency (%) 240V
100W	90.3
225W	92.8
450W	93.6
675W	92.7
850W	91.0

The efficiency results are really good, peaking at around 93.6% between 45-55% load, and dropping to around 91% at full load. A strong set of results.

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
225W	<28
450W	29.7
675W	31.2
850W	37.3

The fan remains disabled at lower loads and it only kicks into action in our environment around 400W-450W load. At usual loads of around 500W-600W the fan is pretty quiet and it is only in the last 10% of load that it ramps up and is clearly audible.

Temperature (c)
	Intake	Exhaust
100W	37	42
225W	38	43
450W	40	48
675W	45	54
850W	46	58

Temperatures inside the chassis remain cool even at higher load levels.

The new ASRock Steel Legend SL-850G has proven to be a very capable power supply in our testing over the last week. The partnership with HEC seems to have worked well for the company, and while we have not had the opportunity to test any other power supplies in their latest Phantom Gaming or Taichi ranges, this Steel Legend unit shows promise that the others will perform well. We can generally tell when a company is cutting corners and ASRock are thankfully not doing this with the SL-850G.

Technically, the SL-850G is a really solid power supply. Load regulation is very good and it passed the strenuous cross load test without any issues. Ripple suppression falls well within industry rated parameters, although it falls short of the best power supplies we have tested this year in that regard. When I say that, I don't mean there are any concerns, just that we have seen better.

This HEC design exhibited no real weaknesses in our testing and it held up well throughout our analysis. Efficiency is very good – hitting over 93% eff. around 45% load. ASRock have an array of heatsinks inside the unit to help cool the components and the running temperatures are good. The high grade fluid dynamic bearing fan remains off until higher loads are demanded and it is never intrusive, even when tasked to around 700 Watts.

Internally, the design incorporates quality 105C rated Japanese branded capacitors. On the primary stage, a Nippon Chemi Con capacitor takes centre stage, rated 400v 560uF from their KMR series. ASRock seem confident that this unit will last a long time as they are backing it up with a 10 year warranty. While this falls a little short of the 12+ year warranties on some other units, it is still reassuring.

While I have no faith in the traditional 80 Plus Ratings, the excellent Cybenetics labs rated this unit as Platinum efficiency and an A+ rating on 230V which is a great series of results.

While availability seems sparse right now, ASRock told me that this unit will be selling for £128.98 in the UK in the coming weeks.

Pros:

• Quiet under load.
• 105C Japanese capacitors used.
• 10 year warranty.
• Fully modular.
• Good quality cables.
• Well finished.

Cons:

• Availability seems an issue right now.

KitGuru says: The ASRock Steel Legend SL-850G delivers solid all round power with very high levels of efficiency. Technically it is a very capable unit and it is also priced very competitively at around £130. It wins our Worth Buying award.

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