More Cardboard Boxes

By Henry, on January 5th, 2014

After having built small cardboard cases for single computers, I tried building single cases for multiple machines. The idea is to share the power supply to reduce cost and increase packing density. For cost reasons, I’ve stuck with microATX motherboards so far, but Mini-ITX seems interesting as they’re smaller and only a little more expensive.

A year ago, I built four Intel LGA1155 systems in a box. Now I’ve added four AMD AM2+/AM3+ systems in a box. Continuing with the unoriginal naming scheme, these systems are named box3 through box6 and box7 through box10, respectively.

Box3-6: Four Intel systems in a box

Box7-10: Four AMD systems in a box

Size comparison: Intel system is more compact.

Size comparison: Intel system (bottom) is more compact.

The Intel systems are more compact because they use smaller heatsinks. The AMD CPUs not only consume more power, but they also need to be kept cooler (around 70°C AMD vs. 100-105°C Intel), causing AMD stock heatsinks to be bigger and louder (7000 RPM vs. ~2100 RPM fans) to handle the greater cooling requirements. The high power consumption meant that there was basically no power headroom to overclock the AMD systems, and I even disabled TurboCore to prevent Vcore from increasing…

	box3	box4-6	box7	box8	box9	box10
Processor	Core i5-2500K @ 4.2 GHz	Core i5-3570K @ 4.2 GHz	Phenom X4 9550 @ 2.2 GHz	Phenom II X6 1090T @ 3.4 GHz	FX-8120 @ 3.4 GHz	FX-8320 @ 3.4 GHz
Motherboard	Biostar TZ77MXE		Asus M3A78-EM	Gigabyte 78LMT-USB3
Power Supply	Antec EA-650 Platinum		Antec EA-650 Platinum
Cooling	4×Stock HSF, 2×Arctic F12 PWM		4×Stock HSF, 2×Arctic F12 CO
Volume	18.8 L		26.7 L
Weight	I didn’t measure		17 lbs
Max Power (wall)	515 W		640 W
Completed	November 2012		January 2014

Power Supply Sharing

ATX power supplies are turned on using Pin 16, PS_ON#. The ATX specification seems to describe this signal as an open-drain output by the motherboard, where the power supply uses a pull-up resistor to hold the line high (+5V). This means it’s possible to just wire all of the ATX connectors together, and the power supply will stay on as long as any of the motherboards pull PS_ON# low. I haven’t noticed any adverse effects of applying power to a motherboard that isn’t requesting it.