SkyHawk GM470 and GM570 Power Supplies Review

Power Supplies by KeithSuppe @ 2006-04-10

Today we have two interesting sub $100 power supplies from Skyhawk, rated at 470 and 570Watt, we put them through their paces on our SLI powered test system to see how they hold up.

Introduction

GM470PC | GM/570PC


Introduction

SkyHawk designs and builds numerous PC products including several Patented accouterments. Their Mini-PC IMC 6389 for Socket-775 incorporates a pre-OS active TFT screen mounted on an electronically operated (lifting) door. SkyHawk also market's several lines of PSU's today were testing two models from the GM-PC Series...

Madshrimps (c)


Our last SkyHawk PSU review featured the GM670SC the unit had the look and feel of raw power but fell slightly short on the 12V rail. In all fairness there were a plethora of components drawing current off the line including an H20 system utilizing the Alphacool AP1510 which uses a 12V ~ 24V which was set to 18V.

Several months prior to the GM670 review we also reviewed the Power One GM620 which was the object of some scrutiny by another site. I criticized that site's review then retracted in the name of harmony, I've regretted that decision which is found in the GM620 Update.

The GM620 wasn't in compliance based on the 240VA safety guideline which then requires split plane PSU’s with multiple 12V-Rails to use independent solder points from the PSU circuit board. Only in this manner can each leg be separate and therefore limited to 240VA and 18A, as is outlined in some of my comments in the article that stirred some controversy covered in the EPS 12V Power Supply Design Guideline (Sec 6.1.1 Split Plane .pdf). Sky Hawk’s failure to meet the guideline was prima facie how and why that article came to be is another story, suffice to say I was a PT writer there and terminated my position shortly thereafter. What was lost in the process of self-promotion at the expense of SkyHawk was an opportunity to critique a questionable Guideline. Sky Hawk's failure to meet that guideline pales in comparison to the damage done to both consumers and the industry by virtue of the Guideline itself. In a multi-rail design regardless of the number of 12V solder points there is till just a single transformer or singular source of 12V current. Multiple solder points from the PSU circuit board do little beyond meeting an impracticable wiring standard for an inefficacious engineering guideline since there's just one transformer and an electronic gate dividing (or switching) current to these 12V rails.

To gain some more insight on the matter, read ”SPCR's Confused about Dual 12V Lines?” this is a clear and well written piece. The photos below were taken of the GM470C reviewed here today; it’s clear SkyHawk has eschewed the 240VA standard using a single solder point.

Madshrimps (c)


Since the advent of the EPS12V PSU guideline PSU design has been hamstring, motherboard makers have been forced to use multi-VRM conversion to alleviate the ripple off the 12V line. These circuits herein lay the quandary, as I've been stating recently the issue has come to a head. With Intel's introduction of the world's first .65-micron process CPU ala Presler, motherboards have been dropping like flies in the stability department and in many cases without any overclocking or over-volting involved. Today’s units at 570 and 470 Watts wouldn't be recommended for a Dual Core processor such as the Intel Pentium-D. Today we'll be testing the GM470 and GM570 on the Asus P5ND2-SLi Deluxe running SLI with two Asus 6600GTs which draw their total current from the PCIe slots.

Packaging

The Power One power supplies arrived in perfect condition.

Madshrimps (c)


As usual Sky hawk does a fine job packaging their units, with bubble wrap, modular cables, mounting screws and an 18-guage power cable.

Madshrimps (c)



A word about power cables

The issue of power cables wasn't something I'd really considered until PSU's reached the 850W level. While that's not relevant here, for future reference at 850W or above when the PSU is drawing peak current a 12-guage power connector would be ideal, 16-gauge is what PCPower&Cooling provided with their TurboCool 850 SSI and I've not had any "noticeable" problems. 18-gauge is about the smallest for any PSU.

Both Skyhawk units are modular, and while there will be power loss on most modular "plugs" the net effect is worth it for the ergonomic benefits. While the PSU doesn't meet all "split plane" requirements it does offer an 8-pin and 4-pinout CPU cables as indicated below.

Madshrimps (c)


I always prefer a power switch on the PSU itself. So long as the switch is executed properly there's no need to unplug the PSU to clear your CMS or change out graphics cards. Be sure to turn off the switch then depress the main power switch on your PC-case to discharge any residual current from the capacitors. I've seen some PSU's have enough left to spin and illuminate an LED case fan for a few seconds.

Madshrimps (c)


The blue LED does give the unit a pleasant appearance in conjunction with its brushed steel exterior.

Madshrimps (c)


The cabling provided with both units is identical: 2x S-ATA ( 2x S-ATA connectors per cable), 2x Molex (2x molex connectors per cable) and finally one PCIe cable, with a single 6-pin connector. Obviously Sky Hawk didn't intend the GM470PC or GM570PC to power an SLI system. Of course that's exactly what I did in the spirit of stress-testing. I use a pair of Asus N6600GT Extremes which do not require a 6-pin external power source. No doubt the additional 75W PCIe slot will tax each PSU when used.

Madshrimps (c)


Specifications

Since both units are new Sky Hawk has not listed any specs on their site just yet although the stickers found on the PSU's have most pertinent info. Clicking on the thumbnails below will provide a close-up of each PSU specifications.

GM470PC | GM570PC

Madshrimps (c) Madshrimps (c)


For more info Sky Hawk has supplied GM470PC/GM570PC Datasheets (.pdf).

Sky Hawk's thinking "inside the box..." ->

Internal Circuitry

Popping Hoods

Madshrimps (c)


The differences between the GM470PC and GM570PC are subtle but just recognizable. There's plenty of room under the hood, which did trouble me somewhat in a casing this size. Taking a closer look we find the secondary inductors differ on each unit. I've outlined these differences focusing on the output stage capacitance and inductor. Below the GM470PC has been outlined in green.

Madshrimps (c)


Next we have the GM570PC it’s evident the secondary inductor on its output stage is somewhat larger. Below the capacitor arrangement and inductor have been outlined in orange.

Madshrimps (c)


The GM470PC from a side view.

Madshrimps (c)


The GM570PC from a side view

Madshrimps (c)


Looking at the G470PC from the AC input stage (bottom right), the green and blue wires can be seen running from the AC-inlet on the opposite end (top right) over the heat spreaders to the thyristor and bridge rectifier stage. The rectifier seems to have a heatsink on it which may be indicative of a design compromise.

Madshrimps (c)


As stated earlier the G570PC from the same angle shows the topology to be identical in both power supplies, with a slightly different parts spec. Note the rectifier (also heat-sinked) is much larger on the GM570 although capacitance remains equal.

Madshrimps (c)



Tests / Conclusion

Madshrimps (c)


Test Methodology


Utilizing Extech's MiniTec MN26 digital Multimeter the positive probe was inserted into the ATX connector with the ground probe against the case. The photo above is simply for reference. Using this method each rail can be tested under IDLE and LOAD.

Intel Test System
CPU Pentium 630 Retail (SL7Z9 3.0GHz 2MB L2 1.25V ~ 1.388Vcore) Socket-775
Mainboards Asus P5ND2-SLI Deluxe (BIOS 0605)
Memory Crucial Tracer Ballistix 5300 (2x512MB DC CL4-4-4-12)
Graphics 2 x Asus N6600GT (256MB GDDR3) SLI mode
Storage / Optical DrivesMaxtor Ultra 16 300GB S-ATA 150
Maxtor DiamondMax 120GB S-ATA
Plextor DVD/RW SATA
Hitachi GD-8000 DVD/ROM
Power Supply PCPower&Cooling TurboCool 850 SSI
Sky Hawk GM470PC / GM570PC
Cooling Thermaltake Blue Orb II
Operating System Windows XP
CaseThermaltake Kandalf Aluminum Tower
Fan Compliment(Case fans) Sunon 120MM 78CFM (front intake replacement), Hong Shen (Tt) 120mm 37CFM rear exhaust. Hong Shen (Tt) 90mm 27CFM rear exhaust.


Sound measurements

Sky Hawk states at their site the GM series is noiseless since the cooling remains off ( 0dBA) as long as the GM470PC / GM570PC internal temperature is less then <40°C, once the fan is running noise levels can reach a maximum of 30dBA according to their specs.

Using Intelli-Systems AR824 digital sound level meter at 150cm (approx 5ft) from source, the reading was 5dB to 7dB above ambient (42.3dBA) with the fan running. Just about every PSU I've tested recently has been eclipsed in noise by the front intake fan of the case I use, a Sunon 120mm fan which pushes close to 80CFM which doesn’t make it a silent fan.


Multi-meter Volt Readings vs. Asus PC Probe II

Software such as Asus PCProbe II and AI-Booster are only as accurate as the devices (thermistors) and formula (BIOS ver. etc.) written for those devices. Surprisingly Asus's monitoring software is highly accurate coming to within a few tenths of a volt on most readings. I've supplied a few screenshots below as an example of my testing method which involves taking a screenshot of the monitoring software just after recording the digital multimeter readout for each rail. The additional information will help determine the accuracy of the on-board monitoring devices and software (as long as the multimeter itself is accurate).

Voltages were recorded at Idle and under LOAD which was produced using the CPU/Memory system tester S&M. The screenshots below were taken at IDLE and then LOAD on the GM470PC running at default speed (3.0GHz) and default voltages (Vcore. DDR voltage etc.) in SLI mode.

Madshrimps (c)


Below we see S&M in the Power Supply stage which also runs the VGA overheat element in S&M. We see a drop on the GM470PC's 12V line from 11.90V to 11.84V which is within spec.

Madshrimps (c)


Finally our digital multimeter readings obtained by the method mentioned at the top of the page. In the chart below results for both power supplies are included measuring rails and Vcore running our 775-LGA Prescott 630 at 3.0GHz IDLE and 3.0GHz LOAD while the system was in SLI mode.

Madshrimps (c)



Conclusion

Sky Hawk's GM470PC/GM570PC are well organized and well constructed, if on the light side. Noise levels were not an issue insofar as being distracting, yet the fans remained on during 95% of the testing, undoubtedly the result of running in SLI mode. Taping a thermistor to the GM470PC's internal heatsink gave a reading of 51°C. For this reason I wouldn't recommend the GM470PC or GM570PC for a Dual Core overclocking rig, nor a high-end gaming SLI or Cross Fire rig.

While I was able to run the P5ND2-SLI in SLI mode cabling provided wouldn't provide for cards which require external power and any attempt at overclocking resulted in system crash. I chose a system which would take these units to the periphery of performance and did just that. Perhaps the best way I can summarize the "value" of Sky Hawk's GM470PC and GM570PC PSUs would be their price. At $52 and $62 these are for the entry level system, not an overclocking unit, nor a hardcore gaming rig. Four years ago these PSU's would be adequate for any type of system, today their entry level.

Pros
+ Compact, versatile, ergonomically friendly
+ Large 120mm self-regulating fan reasonably quiet.
+ Great price ( GM570PC $62 at MWAVE / GM470PC $52 at MWAVE)

Cons
- Rails slightly low.
- No potentiometers
- Crashed during overclocking in SLI mode.


Unfortunately CPUs such as those marketed by Intel have deflated the performance value of PSU's across the board. I knew things were getting completely out of hand when PCPower&Cooling introduced a 1kW PSU.
Close to a Castle located near Santa Clara California, I picture a modern Day Dr. Frankenstein who in his madness for ample power to bring his Presler made from the failed cores of Net Burst past to life, resort's to harnessing the dark power of nature. The sky above his Laboratory looms ominous, just then an explosive crack is heard as a lightening bolt leaps from his rod on the roof traveling down the wire leads which smoke and shake violently and just about bursting into flames. The energy follows the leads underneath a sheet where they will breathe life into a two-headed creature known as Presler. Igor is running frantically about flipping switches as a flash of blinding light envelopes the operating table, Igor's hair stands on end as the Dr is screaming "It's ALIVE!!!" and all this just to send an email...


Questions/Comments: forum thread
  翻译: