ATX Minimum load calculation

Thread Starter

Binary Buddha

Joined Sep 24, 2016
40
Project Reference: http://www.instructables.com/id/Variable-ATX-bench-powersupply-FabLab-edition/?ALLSTEPS
Power Supply: Thermaltake TR2 600W

So, I'm trying to use the stated power supply in the referenced project. I'm just short of setting up the actual connectors and variable supply circuit. I stopped to test that the power supply wouldn't blow up or catch on fire. I setup the "Power Good" (PG) light and the "Power On" (PO) switch. I setup the dummy load on ATX pins 19(+5V) & 17(GND) from the 20 pin connector using a 10 Ohm resistor.

When I powered it; with caution, the resistor heated up to a glowing red and burned through the heat shrink. I posted a pic of it below.

After re-reading the reference material, the author stated to use the +5V as it has it's highest current. So, just using any +5V with a 10 Ohm resistor won't work I'm assuming. The point behind the resistor is to provide a dummy load to trick the power supply into thinking it's connected to a running motherboard. After check the specs on my power supply my +12V1 pin has the highest MAX current rating of 23A.

So, my question is ... How do I find the minimum load for +12V1?

This site states that 1A is general rule of thumb. While this site says 2A.

Would it be safe to say that calculating for 4A and using a 3 Ohm resistor connecting +12V1 to one of the GND wires would work?
 

Attachments

Dodgydave

Joined Jun 22, 2012
8,295
All the atx psus i have modified, i use a 10 ohms,so on the 5V rail @ 10 ohms is 500mA, you need a 10Watt resistor at minimum for safety .
 

Thread Starter

Binary Buddha

Joined Sep 24, 2016
40
So, I burnt through more resistors. Any idea why? I didn't have a 14 Ohm; so I used a 10 and 3.9 ish. Ignore the crappy job. It's just a test setup.





IMG_0219.JPG
 
Top