Reviews - Corsair VX550W Power Supply Review
Sample Provided by: Corsair (By Oklahoma Wolf - madmat on Tue, Sep-25-2007)

Page 2 -

madmat:

Thanks Wolf.

Now that the VX550W has been set free from it's cardboard prison let's take a closer look at it.

 

The VX550 is resplendent in basic black and spiced up a bit by the racy stripe inspired orange label on both sides. No rail info on the sides, it's on the top where in many cases it will never be seen. Nice honeycomb rear section, color matched grill and well finished with a clean flat black paint job. Not exactly the beauty queen but with a rugged aesthetic that doesn't cause you to wonder what you've gotten yourself into. It might be inexpensive but on looks alone it doesn't look cheap.

Looking at the end of the VX550W I see that it looks scarily familiar. I seem to remember a certain CWT built Tt Toughpower 750W I had that shared the triple toroid choke making a choke sandwich out of a small boxy cap.

     I'm going to spoil things a bit and have a little look see.

 

Sure enough, it's a CWT. The resemblance to the 750W in question doesn't end there. Inside we find the same green tape, same swagged heat sinks and the same little plastic deflector on the fan. This is a nice precursor for things to come.

 

Here we take a look at the cables. The main ATX, EPS/ATX 12V and PCI-e cables are each 24". The SATA drive cables are 28" long to the last connector (each SATA cable has three connectors) and the peripheral cables are 34" to the last connector which is the floppy connector on each cable (each is three molex plus floppy).

Type of connector: Corsair
VX550 W
ATX connector 20+4
2 x 2 4-pin 12V connectors 1*
2 x 4 8-pin Xeon/EPS connector 1*
6-pin Xeon/AUX connector 0
2 x 3 PCIe 1
2 x 4 PCIe 1 X 6+2
5.25" Drive connectors 6
3.5" Drive connectors 2
SATA Drive power connectors 6
Fan only connectors (thermostatically controlled 12V only) 0
*Note that the EPS and ATX12V are in 4+4 configuration

The cable load out is perfect for a 550W PSU. No need for a dozen drive connectors or four PCI-e connectors, this baby is aimed at users needing a strong reliable PSU for a midrange PC. If you've got SLI GTS cards or a single GTX card (or even 2900XT) you're good to go. This isn't designed for a server, rather it's designed for an enthusiast's PC and it will do swimingly if my initial impressions are correct.
I'd like to cover my testing methodology first. For testing I'm using a SunMoon SM-268+ ATE (active test equipment) to load up to six rails at five preset loads. I'm also using a USB Instruments DS12M Stingray USB O-scope to log the ripple which I'm saving as an image file. I used to run five tests as the SM-268 has five preprogrammed tests but I've expanded this to include high 3.3V/5V cross load and high 12V cross load testing. Test six is the high 3.3V/5V cross load and test seven is the high 12V cross load. Now, on with the show!

Results from Corsair VX550W COLD load tests
Test
#
+3.3V +5V +12V DC Watts/
AC Watts
Eff. P.F. Intake/
Exhaust
Simulated system load tests
Test
1
2A 3A 4A 87.2W/
109W
80% .97 25°C/
35°C
3.37V 5.15V 12.21V
Test
2
5A 7A 8A 166.4W/
201W
83% .99 24°C/
34°C
3.35V 5.13V 12.19V
Test
3
6A 8A 20A 320.6W/
381W
84% .99 23°C/
35°C
3.33V 5.11V 12.17V
Test
4
10A 12A 30A 474.5W/
576W
82% .99 22°C/
35°C
3.30V 5.09V 12.14V
Test
5
5A 5A 41A 556.1W/
679W
82% .99 23°C/
36°C
3.31V 5.09V 12.14V
Test
6
15A 20A 2A 192.3W/
247W
78% .99 24°C/
36°C
3.32V 5.10V 12.17V
Test
7
1A 1A 41A 522.9W/
635W
82% .99 24°C/
36°C
3.33V 5.11V 12.15V


I'm pretty impressed with the Corsair VX550W. The rails are nice and stable plus they're well regulated and the efficiency holds up real well in all the tests aside from the high 3.3V/5V test. There it drops to 78% (somebody get a rope!) but it makes amends by going back up to 82% on the high 12V test. The VX550W has to be a independent regulation design owing to how well regulated it is. The voltages never do any whoopty-do's during the cross load tests. Oddly the temps are pretty high on the exhaust side of the unit with it swinging back and forth between 12 and 13 degrees C on the delta from the intake. Note how the temps drop on the intake side of things. It's not that the little mod-shop of horrors cooled off as the tests progressed, it's that the fan started pulling enough air from the room to cool the area it was in. Yes, the fan moves some serious air and ramps steadily as the loads exceed 100W so it seems that the unit has both temp and load monitoring for the fan speed. Either that or the temp diode for the fan is located in a spot that doesn't get a lot of airflow. I'll elaborate on this when we move into the hot testing. Anyway, I'm impressed with the VX550W. She puts out 556W at a load that calculated by A*V for all rails driven (at spec voltages) should have been 548W. Neat, it actually exceeds it's rating which is a refreshing change.

Results from Corsair VX550W HOT load tests
Test
#
+3.3V +5V +12V DC Watts/
AC Watts
Eff. P.F. Intake/
Exhaust
Simulated system load tests
Test
1
2A 3A 4A 87.1W/
109W
80% .97 31°C/
33°C
3.36V 5.14V 12.21V
Test
2
5A 7A 8A 166.2W/
201W
83% .99 31°C/
35°C
3.35V 5.12V 12.18V
Test
3
6A 8A 20A 320.3W/
382W
84% .99 33°C/
37°C
3.33V 5.10V 12.15V
Test
4
10A 12A 30A 473.9W/
577W
82% .99 34°C/
38°C
3.29V 5.06V 12.13V
Test
5
5A 5A 41A 555.4W/
676W
82% .99 37°C/
41°C
3.31V 5.08V 12.13V
Test
6
15A 20A 2A 191.3W/
248W
77% .99 36°C/
40°C
3.30V 5.06V 12.17V
Test
7
1A 1A 41A 522.4W/
635W
82% .99 36°C/
40°C
3.32V 5.09V 12.14V


Moving on to the HOT side of things we'll see that the VX550W keeps it's cool as the heat is poured on. The efficiency remains nearly unchanged except in that pesky crossload test and it falls a point to 77%. The stability and regulation remain basically unchanged. The moral of the story is, while the rails won't give a crap about running in a high 3.3V/5V environment, the efficiency will suffer. Not as bad as the older generation of PSU's out there (75% or so average efficiency anyone?) you just will take a hit compared to running it on the, now standard, 12V heavy systems that we see across the PC realm. The VX550W is pretty much unconcerned with the hot box,losing a mere 1.5W on test 5 and still being above it's rating. Pretty impressive showing for a "budget PSU". Ok, since I brought up 12V heavy systems, I'd like to point something out here. See how we have 41A on the 12V rail? When were utilizing that full 41A we've just got a paltry 5A on both the 5V rails and 3.3V rails to work with. I'm pointing this out for the sake of the people that swear vehemently that there's no need for PSU's over 600W-700W. The truth is that if you build a PC that has the capacity to pull a 41A load on start up you're left with the 183 (or there abouts) watts for the rest of the PC. The thing is when you're pulling 41A, say at start up with a quad core and a bunch of drives during boot up, you're going to be overloading your PSU because those drives will pull more than the 25W left for it and the ram could easily overwhelm the 16.5W left to it. I understand that we're talking about way more drives than the average enthusiast will use but there are extremists everywhere (just look around you) and there are guys that do use tons of drives, I know of several personally. This leaves you the choice of buying a monster PSU or a raid controller with a built in processor that supports staggered spin up. Thing is, the controller card could run you more than a monster PSU would. Yikes!

I talked about the cooling in the cold tests, here we see something that supports my hypothesis. Look at the temp delta between the exhaust and intake; nearly a third across the board except in the first test where it was one quarter of the delta in the corresponding cold test. This is where I get my conclusion that it monitors temp and load or the temp diode is in a poorly cooled part of the PSU. Either way the end result would be that the fan spun faster and to a higher level than during the cold tests. In the cold tests the fan made a pronounced jump in speed going from test 3 to test 4. I'd say it spun up about 20% higher than about 5 seconds into test 4 and stayed at a steady level. Same went for test 5. By that time the fan was up to as high as it would go for that temp level and stayed there through tests 6 and 7. The breeze wasn't very great during the cold tests. During the hot tests the fan was up to the level I saw in test 4 of the cold testing and kept gaining RPM as the heat came up. I never really saw a pronounced plateau until the speed leveled off in test 5. By that time I had to assume it was at full speed as it was blowing a strong enough breeze to blow the accumulated minutiae around on my test bench. One thing I wasn't impressed with was the fact that CWT is still using the plastic sheet across the fan splitting it in half as a deflector. Guys, it doesn't really help. We saw that with the Precise you could use a good 120mm fan to cool a very strong PSU. I'm willing to bet that the fan in the VX550W would be up to the task of keeping it nicely cool without the deflector. It's not that I'm arguing it makes no difference if the deflector's there or not but it adds something else that could fail and fail in a non threatening but highly annoying manner.

Corsair VX550W

+3.3V

+5V

+12V

Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7



Looking at the ripple I'm simply at a lack for words over how well it does under all loads. The 3.3V and 5V rails start out at < 12% and never go above that by very much. Looking at the thumbs for the o-scope it looks like I'm using the same shots for all the 3.3V and 5V tests. The 12V rail hits around 60mV but that's it. Half the spec and it's an oddly relaxed looking waveform. Not high frequency like what you'd picture static to look like if it was represented on a scope but more like an AC waveform. Seeing that doesn't make me feel as anxious as the waveform with smaller, closer spikes does. To me when I see a waveform like that it makes me feel like something is running at the ragged edge.

Overall the VX550W exceeds all expectations for a PSU that doesn't really lay a heavy price to performance ratio penalty on the buyer. At sub $100 it's a very tough act to beat.



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