[weblacky]

Since I use the famous fuel ATX adapter I found the exact same model of power supply in a higher wattage from the exact same company meant for PCs and used that. I believe I'm using FSP750-80EPN. See the fuel has several different power supplies and I wasn't sure if the hanger system, that is the giant metal flap on the front of it that screws into the power supply to hang it from the center of the frame, is going to meet up with another manufacturers unit.

Since my original power supply was made by FSP I found the exact body shape in the ATX version of FSP. I also found out that the PC version has the same two holes in the front so I was able to directly screw in the original SGI hanger for original mounting.

This PSU is also much more powerful than the original OEM. And does just meet the minimum ATX adapter recommendations.

In regards to your question SGI's use a huge amount of 3.3 and 5V power. It's exactly because they do not contain as many VRM's in the same way that PCs and servers do. Most modern computers take a higher voltage and regulate it to a lower voltage to use internally. SGI engineers did not do this instead they take power directly from the power supply and use it directly on most of the electronics.

Yes there are VRM's in SGIs but they're mainly lower voltages such as RAM and other low-voltage chips. And they tend to pull from the 3.3V or 5V lines to create those lower voltages.

I agree that by the time the Fuel/Tezro came around they really should've just taken ATX 12V and pull down what they need. But all the prior designs seem to use the power directly from the power supply to be native board compatible. That means a lot of 3.3v and 5V instead of 12v.

If you use a sparkle power supply instead of FSP I'd advise you to track down the sparkle PC PSU, just to make sure the holes match up. I've only owned one Fuel and I've only had an FSP. These power supplies are old and I bought them used from eBay for ultra cheap and they were super clean inside. So because they were so cheap it kept the cost down from trying to buy a modern 700W or better power supply.

Entire ATX conversion cost me about $120 USD!

My two cents...