Gigabyte UD850GM Power Supply Review

The Gigabyte UD850GM survived all of our tough tests.

Gigabyte UD850GM
(Image: © Tom's Hardware)

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Protection Features

Check out our PSUs 101 article to learn more about PSU protection features.

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Row 0 - Cell 0 Protection Features
OCP (Cold @ 26°C)12V: 93A (131.36%), 11.992V
5V: 23.3A (116.5%), 5.093V
3.3V: 22.1A (110.5%), 3.370V
5VSB: 4.4A (146.67%), 4.937V
OCP (Hot @ 41°C)12V: 92.6A (130.79%), 11.997V
5V: 23.3A (116.5%), 5.093V
3.3V: 22.2A (111%), 3.371V
5VSB: 4.4A (146.67%), 4.937V
OPP (Cold @ 25°C)1097.93W (129.17%)
OPP (Hot @ 41°C)1077.9W (126.81%)
OTP✓ (147°C @ 12V Heat Sink)
SCP12V to Earth: ✓
5V to Earth: ✓
3.3V to Earth: ✓
5VSB to Earth: ✓
-12V to Earth: ✓
PWR_OKProper operation
Inrush: NTC Thermistor & Bypass relay

The OCP and OPP triggering points are correctly set; MEIC did a fine job this time. There is also over-temperature protection, which is essential. 

DC Power Sequencing

According to Intel's most recent Power Supply Design Guide (revision 1.4), the +12V and 5V outputs must be equal to or greater than the 3.3V rail at all times. Unfortunately, Intel doesn't mention why it is so important to always keep the 3.3V rail's voltage lower than the levels of the other two outputs.

No problems here since the 3.3V rail is always lower than the other two. 

Cross Load Tests

To generate the following charts, we set our loaders to auto mode through custom-made software before trying more than 25,000 possible load combinations with the +12V, 5V, and 3.3V rails. The deviations in each chart below are calculated by taking the nominal values of the rails (12V, 5V, and 3.3V) as point zero. The ambient temperature during testing was between 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit).

Load Regulation Charts

Efficiency Graph

(Image credit: Tom's Hardware)

Ripple Graphs

The lower the power supply's ripple, the more stable the system will be. In addition, less stress will also be applied to its components.

Infrared Images

We apply a half-load for 10 minutes with the PSU's top cover and cooling fan removed before taking photos with a modified Fluke Ti480 PRO camera that delivers an IR resolution of 640x480 (307,200 pixels).

The temperatures stay low, despite the tough conditions. 

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Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.