SGI 320

SGI did a 'solder hack' on many of the v006 motherboards for the SGI320 to enable the embedded voltage regulator circuit to support the P3 Coppermine processors. This hack involves alterations to the connections of pins 1-4 of U37 (Cherry CS5155 Buck Controller).

Procedure

In order to carry out the modification, first you must locate the U37 chip. After you have unplugged the workstation from the mains, remove the cover and look straight down at the motherboard, near the VRM socket area. Directly to the left you will find a microchip with 8 pins, eight on either side. This is the chip we will be focusing on.

The four pins we need to solder/desolder are pins #1 to #4. Before any new connections can be made, old ones need to be broken. Pins #1 and #3 need to be carefully de-soldered and lifted from their pads. Then the pins are twisted and soldered on neighbouring pin #2.

Then pin #4 needs to be desoldered from its pad and lifted. Finally, a tiny piece of wire is soldered from pin #4 to the pad where pin #3 was connected.

The red dots represent solder pads on the motherboard. Red lines are new connections. The schematic diagrams below show before and after stages of the motherboard hack.

Circuit board before 'solder hack'

Circuit board after completed 'solder hack'

For reference

WARNING: This information is provided by Bob Skiles 'as is' who takes no responsibility for any damage that may occur as a result of this modification. Following this procedure will invalidate any support contract you may have from SGI. Please take maximum caution when performing such an upgrade and make sure that the workstation is unplugged from the mains.

If the idea of soldering your own motherboard sounds daunting then email Bob directly
and he will be sure to offer a competitively priced 'upgraded'motherboard.