interesting, makes me glad all my socket 8 boards are ATX

maxtherabbit wrote on 2026-10-25, 14:37:

interesting, makes me glad all my socket 8 boards are ATX

Especially if they're Duels!

My other Socket 8 system's also ATX. (Well it has both options)

Irinikus wrote on 2026-10-17, 07:48:

There are two types of electrolytic caps on this card, but both types have the same value: 1000MFD 6.3V 105 Degrees Centigrade ...

... Can someone please explain what the difference between these two types of cap is? (As the one type is considerably taller than the other.)

Everything else being equal, the larger the cap can, the lower the ESR.

The black smaller ones are filtering the input to the CPU VRM High FETs. Here low ESR is desirable, but not so critical.

The green tall ones are filtering the output from the VRM Low FETs to the CPU. As low as possible ESR is critical here.

Irinikus wrote on 2026-10-17, 07:48:

... I just ordered 10 of these EEUFR1C102LB's to replace the VRM caps, they're more substantial than the EEUFR0J102's (I'm doing this just for good measure) ...

^ Well done 👍 , the 1C102L are ESR= 30 mΩ, about half than the 0J102 (56 mΩ), and thus better suited for CPU VRM output (replacing the 10 green Sanyos).

It’s been re capped and the extra power wiring is installed, I just need to fit and crimp male 4-pin MOLEX connectors!

That was a lot of work!

speaking of power, the current power supply that I have fitted can only supply 5V@20A maximum, and this thing needs at least 30A on the 5V rail, so I've ordered one of these industrial power supplies, which gives me 30A on the 5V rail and it also gives me -5V, for what it's worth: (FSP FSP300-60ATV (PF) 300W Industrial Computer Standard Power Supply)

Judging by the gauge of the cables, this thing should be up to the task!

Here’s how I wired the extra 5V couplings up:

Nice work!

Just came to wonder if you could've fed the 5V directly onto the CPU daughterboard in stead, thus also eliminating resistance in the edge connector.

H3nrik V! wrote on Yesterday, 12:01:

Nice work!

Thanks! 😀

H3nrik V! wrote on Yesterday, 12:01:

Just came to wonder if you could've fed the 5V directly onto the CPU daughterboard in stead, thus also eliminating resistance in the edge connector.

We have discussed this possibility on the Silicon Graphics User Group Discord.
It may be worth looking into, especially if you want to do some overclocking. (These CPU's ran stably @ 233MHZ in my other machine.)
The issue is: wether it can be done neatly and non-invasively.

Nice project! Thank you for sharing it with us.

I have a K6 CPU module that is powered by a separate 5v wire. At first I had it plugged into a spare molex, then I found a convenient place to attach it on the main board. On your dual setup there are probably multiple places you could attach supplemental 5v power directly to the CPU board. Do you have a picture of the back side? One easy way to see if it would help is to measure the voltage on a running system. If you can carefully probe some of the input capacitors on the VRMs while it is under load, you can see how much voltage drop there is between the power supply and the VRM. I had one upgrade CPU module that would droop to almost 4v under load without additional 5v wires connected. An extra un-connected molex can be used to measure the voltage from the power supply (vs what you measure at the CPU VRM).

Irinikus wrote on 2026-10-26, 14:49:

speaking of power, the current power supply that I have fitted can only supply 5V@20A maximum, and this thing needs at least 30A on the 5V rail, so I've ordered one of these industrial power supplies, which gives me 30A on the 5V rail and it also gives me -5V, for what it's worth: (FSP FSP300-60ATV (PF) 300W Industrial Computer Standard Power Supply)

That is a very OLD STOCK (read: 2003 or older, depending on revision) part and you will need to preemptively re-cap it.

Also, the FSP units of that era use the old fashioned standby circuit which gets hot even when the PC is powered off. Make sure to use high endurance caps in that area (usually it's two 6.3V/10V 1000uF, as well as some small 6mm and 5mm parts near where the purple wire is soldered into on the PCB).

mockingbird wrote on Yesterday, 21:26:

Irinikus wrote on 2026-10-26, 14:49:

speaking of power, the current power supply that I have fitted can only supply 5V@20A maximum, and this thing needs at least 30A on the 5V rail, so I've ordered one of these industrial power supplies, which gives me 30A on the 5V rail and it also gives me -5V, for what it's worth: (FSP FSP300-60ATV (PF) 300W Industrial Computer Standard Power Supply)

That is a very OLD STOCK (read: 2003 or older, depending on revision) part and you will need to preemptively re-cap it.

Also, the FSP units of that era use the old fashioned standby circuit which gets hot even when the PC is powered off. Make sure to use high endurance caps in that area (usually it's two 6.3V/10V 1000uF, as well as some small 6mm and 5mm parts near where the purple wire is soldered into on the PCB).

Here’s the back side of the CPU card: (looking for a good point to attach an additional power coupling)

The ground is easily identifiable. (The soldered in bases of the heatsinks)

Just to find a good contact onto the 5V plane?