smj wrote:
you might want to check out
this thread on Fuel PSUs for general info and possible alternatives.
The ATX specs have allowed (but not required) PSU fan and power monitoring since 2.1. (see subsection 4.2):
http://www.formfactors.org/developer/specs/atx2_1.pdf There's a little more info on the function of those optional ATX power supply signaling here:
http://www.freeopenbook.com/pc-hardware ... 6-TABLE-14Quote:
ATX Optional Power Supply Connector signals perform the following functions:
FanM
FanM is a 2-pulse/revolution signal generated by the power supply fan that notifies the system of current fan speed. If this signal drops, the motherboard realizes immediately that the power supply fan has failed, and can shut down the system in an orderly manner.
FanC
FanC is an optional signal generated by some motherboards to control fan speed for power supplies that are designed to allow this. The signal can range from 0VDC to +12VDC. A signal of +1V or less is recognized by the fan as an order to shut down, and a signal of +10.5V or more is recognized as an order to run at full speed. Intermediate voltage levels, which are supported by some motherboards and some fans, allow the system to instruct the fan to run at some intermediate speed. If this signal is left open (0VDC), properly designed fans run at full speed.
Sense
This is a supplementary +3.3VDC remote sense line, which allows the power supply to monitor the actual voltage at the motherboard connector of the nominal +3.3VDC rail and adjust it to stay within specifications.
and even more in this document:
http://ww1.microchip.com/downloads/en/A ... 00764b.pdf Whether or not the Sparkle or any of the other Fuel power supplies provide (or use) any of these optional ATX signalling functions remains to be discovered.
The Fuel env, serial all, and hinv commands don't return anything related to the power supply that are part number specific (like some previous models have done), so there's at least a remote chance the optional ATX 2.1 PSU monitoring might provide the necessary info to the L1.
The strongest argument for an SGI-only power supply
is jan-jaap's experience with the PS in his prototype Fuel becoming unrecognized after a firmware upgrade - which strongly suggests there's additional outside of the ATX-spec monitoring going on. But it might also be possible that j-j's pre-production prototype Fuel didn't include a PS with ATX2.1 fan and power monitoring capabilities. Monitoring capabilities that weren't expected by his original prototype firmware, but were expected by the later general-release firmware he flashed in. I only suggest this possibility because it seems improbable that Sparkle would have made two different power supplies with the same part number, one with I2C or similar circuitry, and another without this modification. If they'd made a one-off PS for SGI you think they'd have given a unique part number and raised the price accordingly.
Additional background reading - power supplies are discussed but I didn't catch a mention if any were the non-SGI Sparkle FSP460-60PFN (or included the optional ATX2.1 monitoring circuitry):
viewtopic.php?f=3&t=10849viewtopic.php?f=4&t=14990&So the unknown elements are how the L1/environmental monitoring circuitry in the Fuel obtains sense info from the PS, and whether the Sparkle FSP460-60PFN sold to SGI differs internally (beyond the MB connector pin-out) from the non-SGI Sparkle FSP460-60PFN sold to other vendors/the public.
Until that can be determined I wouldn't throw any serious money at a non-SGI ATX/EPS power supply. A Sparkle with the same model number as the one used in the Fuel (FSP460-60PFN) just sold on eBay for $9 - perhaps there'll be more with similar prices.
http://cgi.ebay.com/460Watts-Power-Supp ... 0725423723