To use the PSU tester, simply make the necessary connections to the unit then supply power to the PSU and the tester comes to life. Well, not today. I am not sure what the problem is, but when I would supply power to the PSU, it would flicker on for a split second then shut off. I tried a different power supply and it worked fine... and I already knew that the ModXStream worked since I did system testing first. I tried several times, adjusting the power connections but try as I might, it didn't work. Like I said, I have no idea what the problem is; this is the first time this has happened where the power supply actually works fine. Strange.
Anyway, let's move on to the actual system testing. I will be testing the ModXStream using my dedicated testing computer, which consists of the following hardware:
Intel Core 2 Duo E6600 @ 3.5 GHz
Ultra Products ChillTec Thermo Electric CPU Cooler
EVGA 680i SLI Motherboard
8800 GTX VGA card
2 Gb OCZ Reaper PC2-6400 Memory
74 Gb Western Digital Raptor 10k RPM HDD
Lite-On Optical Drive
HighSpeedPC Tech Station
Normally, I would test a power supply with two 8800 GTX cards in SLI, but since this unit only has two PCI-E connectors and a mere four 4-pin Molex connectors, this was not possible as I simply didn't have enough Molex connectors to use with my Molex-to-PCI-E adapters.
I used a digital multimeter to obtain voltage readings. Since most power supplies correct any fluctuation in the current to the rails before our multimeters would even notice, we're unable to monitor every output in real-time simultaneously. To record idle voltages, I let the system sit idle in Windows for 20 minutes. For load voltages, I ran Prime 95 (one instance per core), Winamp, and defragmented the hard drive, all while playing the DIRT demo on max graphics settings. This combination of programs put a nice load on the system. Below are some photos and the results from my testing.
Voltage testing reveals a very stable power supply. There was only slight fluctuation in the 12v line; certainly nothing to be concerned about. The overall 12v readings are a little on the high side, but still well within spec.
At the end of the day, this power supply has a lot going for it. The unit itself is standard size and looks very nice with the flat black paint job. The 120mm thermally-controlled blue LED fan is as-advertised; very quiet. A free-flowing honeycomb style grill in the rear makes for an easy exit point for the fan to exhaust the heated air. A modular cable system makes wiring a breeze, allowing you to eliminate the cables that you do not need, thus helping to prevent cable clutter. The cables are very nice and have plenty of length. All cables are sleeved in black mesh and the 4-pin Molex adapters use quick-release fittings.
My only concern with the ModXStream 780 is the lack of available 4-pin Molex connectors. The unit only supplies four adapters; this may be enough for some, but I suspect most users (myself included) will certainly need more than this. And, if you are running two high end graphics cards that require two PCI-E connectors each, well, you better have a couple Molex-to-PCI-E adapters and several Y-splitters handy or you will be out of luck.
As of writing, the ModXStream 780w power supply sells for around $180.00 USD at a popular online reseller. Thanks to OCZ Technology for providing us with this review sample.