Corsair HX620W Modular Power Supply

Corsair is reknown for their memory products, however, as of today they are entering
a new market segment with the introduction of a new line of modular power supplies,
the HX Series. Here is a first hand look at the HX620W modular power supply from Corsair Memory.
A 520W version (HX520W) is also available.

Unlike the trend for gimmicky looks in power supplies, the Corsair HX power supplies
have a more serious look with a durable matte/satin black textured finish and either
red (HX620W) or yellow (HX520W) labelling. The mono-chrome scheme is followed through
right down to the black fan grill, the permanently connected power cables are loomed
in black, and all-black modular cables and connectors complete the look.

Included in the box are a handy bag to store unused modular cables, tie straps
to aid in cable management, mounting screws, power cable, a Corsair case badge and
a slew of modular cables that will accommodate just about any conceivable system.
For added convenience, all 4-pin molex connectors have thumb grips.

Modular cables include:

• (2) SATA cables with 3x connectors (33″ long)
• (1) SATA cable with 2x connectors (27″ long)
• (2) Standard 4-pin molex with 3x connectors (32″ long)
• (2) Standard 4-pin molex with 2x connectors (19″ long)
• (2) PCI-e power connectors (23″ long)
• (1) 4-pin to (2x) 4-pin Y-adapter for fans (8″ long)
• (1) 4-pin to (2x) FDD power Y-adapter (7″ long)

Permanently attached cables are all approximately 21″ and include:

• 20+4 pin EATX
• 8-pin EPS
• 4-pin ATX

Why separate 8-pin EPS and 4-pin ATX instead of a combinable 4+4 connector that has
been common as of late? Corsair confirmed that upcoming server motherboards will
require both 8-pin and 4-pin connectors.

Powerful – The HX Series efficiently delivers continuous full rated output
with solid triple +12V rails for a combined maximum output rating of 50A (40A on 520W),
and is engineered to exceed the requirements for even the most power hungry computers.

Efficient – Utilizing advanced double-forward switching circuitry design,
the HX series provides 80%+ high efficiency and Active Power Factor Correction (PFC),
ensuring the PSU generates minimal heat during operation and uses less electricity.

Customizable – The enhanced modular cable solution provides flexible cables
for superior cable routing. This eliminates cable clusters and optimizes the airflow
inside your case.

Quiet and Cool – The high quality thermally controlled double ball-bearing
120mm fan delivers excellent air flow with whisper quiet operation.

Dual GPU Ready – The HX Series offers native support for dual graphics
card configurations with two PCI-Express cables and high performance +12V rails.
It is compatible with either nVidia’s SLI or ATI’s Crossfire solution.

• Supports the latest ATX12V v2.2 and EPS12V 2.91 standards and is backwards compatible with
  ATX12V 2.01 systems.
• Guaranteed to deliver rated specifications at 50C.
• Active Power Factor Correction with PF value=0.99 provides clean and reliable power to your system.
• Double forward switching circuitry design offers high efficiency, up to 84% under wide load range.
• 8 Serial ATA connectors (4 on 520W).
• 105 C rated industrial grade capacitors provide uncompromised performance and reliability,
  delivering 4 times the lifespan of conventional 85 C rated capacitors.
• Triple 12V Rails provide independent reliable power to the CPU, video card and other components
  with a combined rating of 50A maximum! Advanced circuitry design that automatically enable
  power sharing between the triple +12V rails in an event of overload on any single +12V rail.
• Ultra quiet 120mm double ball-bearing fan delivers excellent airflow at an exceptionally low noise
  level by varying the RPM in response to temperature.
• Powerful +5Vsb rail with 3A rating.
• Auto switching circuitry provide universal AC input 90~264V.
• Over Current/Voltage/Power Protection, Under Voltage Protection, and Short Circuit Protection
  provide maximum safety for your critical system components.
• Gold Plated connectors provide oxide free ultra low-resistance contact between the power supply
  and your critical components.
• Dimension: 5.9″(W) x 3.4″(H) X 5.9″(L) 150mm(W) x 86mm(H) x 150mm(L)
• MTBF: 100,000 Hours
• Industry leading 5-year (60 month) warranty.

Both Corsair HX power supplies feature triple 12V rails that can share power in
the event of one 12V rail being overloaded. Unlike most other multiple 12V rail
PSUs that can combine rails, 12V rail sharing on the HX Series is handled completely
by internal circuitry, no manual configuring is necessary.

The three 12V rails are divided up in a way to spread what would be the heaviest
loads in quite an efficient manner. 12V1 powers one PCIe connector, the 24-pin EATX
connector and 2 sets of power connectors (4-pin molex/SATA). 12V2 powers the other
PCIe connector, half of the 8-pin EPS and 3 sets of power connectors (4-pin molex/SATA).
12V3 powers the 4-pin CPU ATX connector and the other 2 pins of the 8-pin EPS connector.

What is important to note here is that each PCIe cable is on a separate 12V rail, making
much more current available to Crossfire or SLI setups than normally found on multi 12V
rail power supplies. PSUs with multiple 12V rails are often frowned upon for dual video
cards systems because splitting rails also means splitting available current. In
most cases, that caps the available current to 18A maximum to be shared between two
video cards. High-end video cards are current hogs and limiting current in such a manner
is often cause for poor performance, poor overclocking or general system instability
when under load. By having each PCIe powered from a separate 18A rail, the HX620W
effectively doubles the maxmimum current available to Crossfire or SLI cards compared to
dual 12V rail power supplies.

Opening the case reveals an ADDA AD1212HB-A71GL 120mm fan that is the sole source
of cooling for the HX power supply. This is a ball bearing fan that runs 2200RPM
and produces 85CFM at 39dB at 12V. The fan is controlled, however, and is so quiet
at lower loads/temperatures that it is completely inaudible. At higher loads and
temperatures, the fan does speed up and keeps temps at a very reasonable level without
much noise. Suffice it to say, with the PSU mounted inside a case and the fact that the
only fan in the PSU is also inside, even at full speed, it is unlikely that the fan
will be heard much or at all outside the PC case.

With the push for efficient power, Corsair does not disappoint with the HX620W.
As can be seen by the chart below, 80% efficiency is maintained or exceeded from
low power draws all the way up to maximmum power ratings.

The internals feature some interesting heatsinks with bent fingers, a clever design
to make room for the fan and take full advantage of it by putting a large surface area
squarely in front of it. Air is then forced out the back of the PSU case through
a honeycomb style mesh. All components are laid out ergonomically on a double-layer
PCB with plenty of room for air to flow around all components.

A huge capacitor dominates the center of the inside and is surrounded by other
server-quality components. Every capacitor, from the biggest to the smallest,
are rated at a whopping 105C, which gives up to four times the life span of the
cheaper and more common 85C rated caps. Use of top-quality components can also be seen
by the fact that Corsair offers an extremely long 5-year warranty on the HX power
supplies.

Test equipment:

• WattsUp? Pro Power Meter (±3% accuracy)
• Extech 22-816 Digital Multimeter
• Resistor Load #1 – 18A
• Resistor Load #2 – 16A
• Resistor Load #3 – 9.6A

Prior to testing the HX620W on a working system, testing was conducted using several
sets of ballast resistors for loading. Three separate loads were used and placed
on each of the three 12V rails. 18A load was placed on 12V1 via the PCIe #1 cable,
16A was placed on the 12V2 via the PCIe #2 cable and 9.6A was placed on 12V3 via the
4-pin CPU ATX cable.

Each load was run for one full hour, after which, the next cumulative load was added.
Total test time was then three hours, with the heaviest static load (528W) being run during
the last hour. Measurements were taken at 30 minute intervals at the 4-pin molexes for all
5V, 12V1 and 12V2, at the EPS/ATX for 12V3 and the EATX for 3.3V. The following chart
represents the average of those measurements for each load.

To add a dynamic load to the equation, two ballast loads were added to the HX620W
power supply while connected to the system as described below and benches were run.
The overclocked x1900XT was run on PCIe #1 (12V1), the 18A ballast load was placed
on PCIe #2 connector (12V2) to simulate a second high-current video card and the 9.6A
load was placed on the 4-pin CPU ATX (12V3).

• Intel Pentium D 930 (Presler) 3.00GHz @ 4.80GHz
• ASUS P5W DH motherboard
• Sapphire x1900XT – single – 700/800 clocks
• 2GB Corsair XMS2 6400C3 memory
• Hitachi Deskstar 160GB SATA HDDs (x2) – no RAID
• Western Digital 120GB IDE HDD
• NEC ND-3550A CD-RW/DVD drive
• Swiftech MCP-350 water pump
• 2x Evercool 120mm fans

Unfortunately, there were no means to accurately measure the total DC power draw
of the entire system. What could be measured on this load was the AC input power,
which averaged 776W during 3D benchmarks. Taking power supply efficiencies into
account using the low end of 80% for near max loads, that would translate into
approximately 620W output to the system.

¹ The 8-pin EPS plug was used on the motherboard, which only has a
4-pin socket. 12.00V as measured with load on 12V3 includes both the overclocked CPU
draw and a static 9.6A from the ballast load on 4-pin CPU ATX plug.

As seen in the static and dynamic results, the Corsair HX620W maintains solid rails,
even near maximum loads with high current pulled simultaneously on all three 12V
rails. The HX620W had no problem running a high-end overclocked system and should
handle even the most demanding Crossfire or SLI setups. That is not a common thing
to hear about any power supply with multiple 12V rails, but the HX620W has definitely
changed my thinking on both multiple 12V and modular power supplies.

With the features and performance of the HX620W, Corsair is entering the power
supply market with a solid PSU that will continue their reputation of producing
high quality and performance gear.

Thanks again to Corsair Memory
for providing this HX620W to test out!

Ross Lapkoff