Re: Recapping help for old DFI boards?

shevalier wrote on 2026-05-15, 03:32:

Re: Recapping help for old DFI boards?

The 3300uF ones are on the 12V rail, right?
Then I'll get the 2700uF 16V polys!

SPiKA85 wrote on 2026-05-15, 04:41:

shevalier wrote on 2026-05-15, 03:32:

Re: Recapping help for old DFI boards?

The 3300uF ones are on the 12V rail, right?
Then I'll get the 2700uF 16V polys!

Can you guess why I’ve fitted 16V polymer capacitors to the VTT (1.25V) and VRAM (3.3V) bus?
It’s because I couldn’t find any other capacitors in the drawer with the ‘relatively blue’ markings and a 5mm (D=10mm) pitch between the terminals.
Input to the VRM (5V bus) – 3 × 470 μF × 6.3 V
Output (CPU power supply) – 2 × 820 μF × 4 V (10 mm) + 2 × 820 μF × 2.5 V (8 mm)
FSB 150 MHz, VRM completely cold.

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all.
There’s no need to think about it at all.
10mm diameter – 1000–2000μF * 6.3V
8mm diameter – 470–820μF * 6.3V
6.3mm diameter – 100μF * 16V.

Count the quantity, place the order.

shevalier wrote on 2026-05-15, 05:08:

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all. There’s no need to think about it at all. 1 […]
Show full quote

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all.
There’s no need to think about it at all.
10mm diameter – 1000–2000μF * 6.3V
8mm diameter – 470–820μF * 6.3V
6.3mm diameter – 100μF * 16V.

Count the quantity, place the order.

So its OK if a replace a 10V Electrolytic with a 6.3V Polymer?

SPiKA85 wrote on 2026-05-15, 05:18:

shevalier wrote on 2026-05-15, 05:08:

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all. There’s no need to think about it at all. 1 […]
Show full quote

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all.
There’s no need to think about it at all.
10mm diameter – 1000–2000μF * 6.3V
8mm diameter – 470–820μF * 6.3V
6.3mm diameter – 100μF * 16V.

Count the quantity, place the order.

So its OK if a replace a 10V Electrolytic with a 6.3V Polymer?

yep
The LowESR 10V electrolytic capacitors are a sort of replacement for the UltraLowESR 6.3V capacitors.
They have roughly the same ESR.
This is an old trick for cutting costs.

It doesn't work with polymercap, their ESR doesn't drop from the rated voltage value

Offtopic: Do you know what are the components in this photo?
Can they be replaced for a more modern looking component? xD

shevalier wrote on 2026-05-15, 05:08:

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all. There’s no need to think about it at all. 1 […]
Show full quote

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all.
There’s no need to think about it at all.
10mm diameter – 1000–2000μF * 6.3V
8mm diameter – 470–820μF * 6.3V
6.3mm diameter – 100μF * 16V.

Count the quantity, place the order.

Does this guideline work for Pentium4 boards too?

SPiKA85 wrote on 2026-05-15, 06:27:

shevalier wrote on 2026-05-15, 05:08:

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all. There’s no need to think about it at all. 1 […]
Show full quote

On Pentium 3 motherboards, there aren’t any large capacitors on the +12V bus at all.
There’s no need to think about it at all.
10mm diameter – 1000–2000μF * 6.3V
8mm diameter – 470–820μF * 6.3V
6.3mm diameter – 100μF * 16V.

Count the quantity, place the order.

Does this guideline work for Pentium4 boards too?

If the motherboard has a PCI-Express connector or a 4-pin CPU connector, there will always be (at least) one 16V capacitor near the slot and two or three near the 4-pin CPU connector.

Everything else is the same.
PS. If you’ve got absolutely nothing else to do, you can always draw up a mega-detailed BOM sheet.
3V capacitors for the CPU, 4V for 3.3V, 6.3V for 5V.
+1 chance of getting confused and buying the wrong parts
+1 cup of coffee saved (But who am I to try to dissuade someone with deviant tendencies? 😀

SPiKA85 wrote on 2026-05-15, 06:13:

Offtopic: Do you know what are the components in this photo?
Can they be replaced for a more modern looking component? xD

These are transistors with TO92 package. There are SMD equivalents, but there is no real comfortable way to solder them in. I'd just straighten them up carefully and that's it.