Corsair HX620 620w Modular PSU Page: 1

Corsair is one of those names that every computer enthusiast would have heard of. Producing high performance memory modules since 1994, Corsair have always provided memory solutions for both the budget user and the extreme overclocker. However, today we're not going to be looking at any of Corsairs memory modules - but instead their newly released HX620 620w modular power supply.

Maybe it's just me, but there seems to be a strange phenomenon taking hold at present where every high-end PC component manufacturer is creating their own line of PSU's. This is certainly no bad thing, as it introduces new competition to the market, driving down the prices of high end power supplies, and forcing existing PSU manufacturers to improve the quality of their units and introduce new features.

Have Corsair done their homework with the HX620? Let's find out...


When the HX620 arrived at my door, I must admit being surprised by the size of the box. Most ~600w units I've reviewed in the past have come in rather minimalistic packaging in an attempt to shave a vital few pence off manufacturing costs.

Corsair HX620 Box Front Corsair HX620 Box Back

The HX620 features a 2-tone black and red theme throughout most of the packaging, with an up-close image of the units modular connector system spanning the front of the box. Overall the packaging is quite simplistic but does give the feeling of a very professional product.

I was extremely impressed to see Corsair providing a 5 year warranty with the HX620 as this is something often only seen on the most expensive server-based power supplies.

Turn the box around and we can see that Corsair have listed the HX620's specifications in English, French and German. Some of the most notable features include: Guaranteed to deliver specifications at 50°c, Supports latest EPS12v standards, Industrial grade capacitors, Compatibility with dual-GPU systems, Gold plated connectors. The first of these specifications (Guaranteed to deliver specifications at 50°c) is very commendable as many other PSU manufacturers rate their power supplies at 30-40°c, which is often below the operating temperature of the unit and leads them to giving the PSU inflated performance figures.

Corsair HX620 Box Open Corsair HX620 Package

Corsair have taken extensive measures to ensure that your HX620 arrives at your door in perfect condition even at the hands of the most brutal courier. The unit has been placed in a double walled cardboard box and is sandwiched between two large foam mouldings that protect all corners of the unit.

Included in the HX620 package are the following items:
• 1x Standard power cord.
• 1x pack of black cable ties.
• 4x ATX case screws.
• 1x HX620 manual (B/W).
• 1x Velcro cable pouch containing modular cables.
• 1x Corsair HX620 620w power supply.

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The following information has been taken directly from Corsair's website:

"From the manufacturer of the "World's Most Awarded Memory" comes the Corsair HX Series Power Supply. With that same legendary focus on the performance and reliability, Corsair has engineered the HX Series to support even the most demanding of systems. The Corsair HX Series incorporates the most advanced technology to deliver reliable, continuous, and efficient power to all critical system components. The HX Series is the ideal power supply for high performance and gaming PCs, Audio/Video workstations, and file servers."

• Supports the latest ATX12V v2.2 and EPS12V 2.91 standards and is backwards compatible with ATX12V 2.01 systems.
• Guaranteed compatibility with dual-GPU configurations.
• Double forward switching circuitry design offers high efficiency, up to 80% under wide load range.
• Active Power Factor Correction with PF value=0.99 provides clean and reliable power to your system.
• Universal AC input 90~264V automatically scans and detects the correct voltage. No more hassle of flipping that tiny red switch!
• Ultra quiet 120mm double ball-bearing fan delivers excellent airflow at an exceptionally low noise level by varying the RPM in response to temperature.
• Guaranteed to deliver rated specifications at 50ºC.
• Triple 12V Rails provide independent reliable power to the CPU, video card and other components with a combined rating of 50A (40A on 520W) maximum! Advanced circuitry design that automatically enables power sharing between the triple +12V rails in an event of overload on any single +12V rail.
• Powerful +5Vsb rail with 3A rating.
• Over Current/Voltage/Power Protection, Under Voltage Protection, and Short Circuit Protection provide maximum safety for your critical system components.
• 105ºC rated industrial grade capacitors provide uncompromised performance and reliability, delivering 4 times the lifespan of conventional 85ºC rated capacitors.
• Enhanced modular flexible cables enable easier cable routing and increased airflow in the system.
• Gold Plated connectors provide oxide free ultra low-resistance contact between the power supply and your critical components.
• 8 Serial ATA connectors (4 on 520W).
• Dimension: 5.9"(W) x 3.4"(H) X 5.9"(L) 150mm(W) x 86mm(H) x 150mm(L)
• MTBF: 100,000 Hours.
• Safety Approvals: UL, CUL, CE, CB, FCC Class B, TÜV, CCC, C-tick.



Noise Level

The HX620 appears to have some very impressive specifications including ~85% efficiency, noise levels of around 35dbA under 100% load and triple +12v rails rated at 18 amps each. Corsair also claims that each of the +12v rails are able to share power, thus meaning that if any one of the 3 rails becomes overloaded, one of the other rails will be able to assist.

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As expected for a ~600w power supply, the HX620 is of standard ATX size. This means that there should be no problems for those of us planning on using the unit inside a case with little space around the PSU area. The HX620 also features an extremely rugged black powder coated finish that I found very resistant to minor knocks and scratches.

Corsair HX620 Bottom Corsair HX620 Back

The bottom of the unit features a 120mm fan placed slightly off-centre to better cool the components contained within. The fan (and your fingers) is protected by a black wire fan grill that sits flush with the casing.

Around the back of the unit we can see that Corsair have gone for the standard honeycomb mesh grill as seen on most other power supplies that utilise a 120mm fan. You may also notice the abundance of a voltage selection switch. This is because the HX620 is able to detect the input voltage (110/240v) and switch accordingly.

Corsair HX620 Top Corsair HX620 Side

They may only be stickers, but the design of the red and black labels placed on the top and sides of the HX620 make it look pretty beastly and certainly a great candidate for my latest case mod project. However, the specification sticker at the top of the unit serves a slightly more important purpose than just aesthetics - detailing the amperage output of the HX620's rails along with the usual warnings about opening the PSU cover.

Corsair HX620 Front

The front of the unit sports 7 modular power connectors, 2 of which are dedicated to providing power to PCI-Express cards. The modular connector type and layout did look very similar to the ones used on the recently reviewed Seasonic M12 unit - lets hope it doesn't suffer from the same issues.

In their wisdom, Corsair have decided not to make the ATX and P4/EPS power cables modular. This is most likely due to problems that can arise if there is poor contact between the ATX/EPS connectors on the motherboard and power supply.

Corsair HX620 620w Modular PSU Page: 4

As I've said in previous modular power supply reviews - some like the idea of modular, some don't. Those in favor of the design are likely to be those who spend hours routing cables behind their motherboards to prevent them from being seen through their case windows. At the opposite end of the scale are the more skeptical PC enthusiasts who believe that the modular cabling system is unreliable and can cause increased resistance where poor connectors are used. In the end it really comes down to the quality and type of connectors the manufacturer has adopted for the unit and how well they have implemented the design.

Corsair HX620 Cable Bag Corsair HX620 Cables

Corsair HX620 Plugged In Corsair HX620 Cable

Corsair have made a departure from the sleeved cabling used by almost all other PSU manufacturers in favor of a moulded plastic, ribon style cable. Not only are these slimmer than the standard sleeved cable (especially when bundled together with a cable tie), but they are also extremely flexible and look very cool. The only disadvantage of course, is that they cannot be easily sleeved in another colour to suit your customised PC.

Corsair HX620 ATX Corsair HX620 EPS12v

The ATX connector on the HX620 is native 24-pin. However, as you can see above, a small block of 4 connectors can be broken off to switch the connector to 20-pin, and thus make it compatible with older motherboards. As many motherboards still make use of the P4-12v 4-Pin connector, Corsair have chosen to include two separate cables for P4-12v (4-pin) and EPS12v (8-pin) standards.

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Looking Inside

After noticing some similarities between the HX620 and the recently reviewed Seasonic M12's modular system, I was very keen to take a look inside the HX620. If indeed it does share similar internal components to the Seasonic M12 then we should see some good results in our tests over the next page.

Corsair HX620 Inside

Corsair HX620 Inside Corsair HX620 Inside

After examining images from our review of the Seasonic M12 against the HX620 it would certainly seem that both units use the same internals with only minor changes. The Corsair HX620 does however have an advantage over the M12 - a more sturdy modular connector backplane that should alleviate the issues we highlighted while trying to plug connectors into the M12.

Just like the Seasonic M12, the HX620 has two yellow transformers placed on the centre of the board. The larger of the two is most likely responsible for the +12v rails with the smaller being responsible for +3.3v and +5.0v rails. Placed in between the transformers is a single brown capacitor that actually looks slightly bigger than the one used on the M12.

Corsair HX620 Fan

Cooling the HX620 is a 120mm fan manufactured by ADDA. This is actually the very same fan found inside the M12, however Corsair in their wisdom decided to do away with the 60mm fan also present in the M12 in favour of a quieter power supply. The fan specifications are as follows:

Model: AD1212HB-A71GL
Size: 120mm x 120mm x 25mm
CFM: 85.2cfm
dBA: 39.1dba
RPM: 2200rpm

More information on ADDA fans can be found here.

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Load Testing

In order for the results from all current and future PSU reviews to remain fair and comparable, Overclock3D uses a custom built Power Supply load stress tester. The tester will be placing the following loads on each of the HX620's rails:

  Idle Load
+3.3v Rail
+5.0v Rail
+12v Rails
10a10a x3

As some power supplies produce obscure voltage outputs when running with 0% load, the Idle testing simulation will be produced by placing each rail under a small load similar to what would be expected from a mid-range PC. Load testing results are obtained by placing the unit under the maximum load selectable on the OC3D equipment without tripping the OLP (Over Load Protection) on the power supply.

Corsair HX620 +3.3v Corsair HX620 +5.0v

Corsair HX620 +12v

Both the +3.3v and +5.0v rails remained well within ATX specifications throughout the testing, with the +5v rail exhibiting the most droop at 0.07v - still a very respectable result for any PSU placed under heavy load.

During the +12v load testing, each of Corsair's three rails (rated at 18amps) were placed under a total load of 30 amps. As a result of this, each rail produced the same voltage output results across the board and therefore only necessitated a single graph as shown above. With a maximum voltage fluctuation of 0.02v, the HX620 shows that it is more than capable of producing stable power to any medium/high-end SLI or Crossfire setup.

Efficiency Testing

Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains against the power (in watts) consumed by the OC3D power supply stress tester. These results may not be 100% accurate, but have proven to be extremely close to results obtained from professional equipment.

Corsair HX620 Efficiency Idle Corsair HX620 Efficiency Load

At idle the HX620 was placed under a total load of 203 watts with a recording of 253 watts consumption being obtained from the mains. Therefore the efficiency of the HX620 at idle worked out to be 80.2%.

Increasing the load on the unit produced even more favourable results, with the HX620 managing 83.8% efficiency when being placed under a total load of 646 watts.

Noise Testing

Possibly the hardest part of any PSU review is summarising the level of noise given out by the unit. The threshold for what is considered 'noisy' varies from person to person and therefore what I may consider a quiet unit, another person may consider extremely loud. A common way to resolve this issue is to use a dBA meter to measure the units noise level, however this doesn't take into account the pitch (type) of noise emitted and whether it is likely to irritate end users.

For this reason OC3D records all power supplies at idle and load in wav format for you to make your own informed decisions. All recordings are taken at 30cm away from the PSU and outside of a PC case. You will need to remember that noise levels will be reduced by varying amounts once the PSU has been installed inside your PC enclosure.

Idle Recording - Download
Load Recording - Download

At idle the HX620 was extremely quiet with the 120mm fan running at a very low RPM. As the load on the unit was increased, the fan gradually gained speed in order to counteract the extra heat produced by the PSU's components. Even at full load the HX620 managed to keep a good balance between the noise and heat output of the unit, proving that Seasonic's implimentation of a 60mm fan on their M12 PSU was not necessarily required.

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Entering the PSU market for the first time Corsair have certainly taken the bull by the horns with their HX620 unit. Managing extremely stable voltages on the +3.3v and +12v rails with only slight droop on the +5v rails, It was hard to find any negative issues to talk about.

The ribbon-style modular cables made a nice change from the nylon sleeving seen on almost other power supplies, and also proved to be more flexible. Corsair also seem to have avoided some of the major issues often found on other modular power supplies with the HX620, which was a great relief.

For a ~600w unit the sum of £96 may seem a little higher than most other competing products, however as the saying goes - "You get what you pay for", and this is certainly true for the HX620.


• Good looks and rugged finish.
• High efficiency at full load.
• Excellent performance on +12v and +3.3v rails.
• Sturdy modular connector system.
• Flexible, ribbon-style cables.
• Well packaged.

• +5.0v rail could have performed better.
• Slightly expensive for a 600w unit (but you get what you pay for!)

Editors Choice

Thanks to Corsair for providing this unit for review.

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