VOGONS


First post, by kupa97

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I have a DFI LANParty UT nF4 Ultra-D with over 40 bad capacitors and I need help buying the right caps to replace them with. I have included a color-coded photo of every single bulging capacitor on this motherboard. All bad caps are Chemi-Con KZG.

I would like to replace these electrolytic caps with polymer, so far I've found the KEMET A750MS108M1CAAE013 1000uF 16v; not sure if that one would work.

Which specifications should I most be paying attention to when replacing electrolytic caps with poly ones? All these numbers are hurting my brain.

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Reply 1 of 13, by kupa97

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BLUE = 470uF 16v 8mm x 11.5mm
GREEN = 1000uF 6.3v 8mm x 11.5mm
PINK = 1500uF 16v 10mm x 19.5mm
RED = 1500uF 6.3v 8mm x 18mm

Reply 2 of 13, by Matth79

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All poly is going to be expensive, and it looks like the most critical VRM caps are already poly (unless they are "fake poly"). Looks like 1500uF 16V is available in poly, at Mouser, the Kemet 1500 16V is decent value but backorder, in stock Chemicon at 8.69 EU/10 while Panasonic low ESR electrolytic is 2.77 EU/10
The 1000 6.3 is what there are most of.. Kemet Poly, 3.90 EU/10 - Low ESR elec, 2.50 EU/10 - the 1500 6.3 seems pretty close

Seems there's more of a premium for the 16V in poly than the 6.3V, and not as expensive as I thought all poly would be, depends on your local supply of course

Reply 3 of 13, by Lostdotfish

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Any decent brand polymers will do. Kemet, Kyocera, Chemi-con etc.

Match the capacitance.

Voltage rating meet or exceed. It doesn't matter if you put a 25v rated cap in place of a 10v rated one.

Match diameter. This will make sure the lead spacing is right.

Watch the height. It doesn't matter if they're shorter but pay close attention to clearance if you go taller (it's unlikely they'll be taller but you can end up with tall caps preventing heatsink installation or expansion card seating etc).

Reply 4 of 13, by kupa97

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Thanks, I'll keep that info in mind.

Reply 5 of 13, by kupa97

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Is the ESR something that I should be paying attention to as well or are all of these poly caps ultra low ESR?

Reply 6 of 13, by kupa97

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Anyways, these are the caps that I'm gonna get; I think they should work fine. Turns out that the KEMET headquarters are a few miles away from where I live in Fort Lauderdale, pretty cool.

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Reply 7 of 13, by Lostdotfish

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kupa97 wrote on 2025-11-24, 23:14:

Is the ESR something that I should be paying attention to as well or are all of these poly caps ultra low ESR?

Polymer caps will be low ESR.

If you go for electrolytic caps, then yes you need low ESR.

Reply 8 of 13, by shevalier

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kupa97 wrote on 2025-11-24, 21:32:

I would like to replace these electrolytic caps with polymer, so far I've found the KEMET A750MS108M1CAAE013 1000uF 16v; not sure if that one would work.

1m5 *16V Poly is something in the language of “the beautiful and rich.”
Such capacitors are only installed on extremely expensive kilowatt PSUs of the latest ATX standard.
In quantities of 1-2 pieces. 😀

Spoiler

24.jpg

Those directly connected to the +12V ATX bus - 470μF*16V (270 for ultra Low ESR)
All others - 560-820*6.3V
Any General Use polymer capacitors of the appropriate diameter will work.

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Reply 9 of 13, by dionb

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kupa97 wrote on 2025-11-24, 23:14:

Is the ESR something that I should be paying attention to as well or are all of these poly caps ultra low ESR?

Generally poly will have much lower ESR than electrolytic. You definitely don't want higher ESR than the original ones, but is the ESR is much lower in the bulk output filter capacitors (the big ones immediately behind the VRM, purple on your pic), it can have unintended consequences for voltage regulation.

Take a look at the datasheet for the Intersil IS6559CB voltage regulator IC on that board:
https://www.alldatasheet.com/datasheet-pdf/vi … SL6559CB-T.html

On pages 15-17 it has a whole section on compensation circuit design for the output filters where the ESR of the filter caps is one of the variables in the equations.

So if in doubt, try to stay as close as possible to the original ESR spec for those big caps.

Reply 10 of 13, by shevalier

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dionb wrote on 2025-11-25, 09:32:
Generally poly will have much lower ESR than electrolytic. You definitely don't want higher ESR than the original ones, but is t […]
Show full quote
kupa97 wrote on 2025-11-24, 23:14:

Is the ESR something that I should be paying attention to as well or are all of these poly caps ultra low ESR?

Generally poly will have much lower ESR than electrolytic. You definitely don't want higher ESR than the original ones, but is the ESR is much lower in the bulk output filter capacitors (the big ones immediately behind the VRM, purple on your pic), it can have unintended consequences for voltage regulation.

Take a look at the datasheet for the Intersil IS6559CB voltage regulator IC on that board:
https://www.alldatasheet.com/datasheet-pdf/vi … SL6559CB-T.html

On pages 15-17 it has a whole section on compensation circuit design for the output filters where the ESR of the filter caps is one of the variables in the equations.

So if in doubt, try to stay as close as possible to the original ESR spec for those big caps.

General use polymer capacitors are essentially direct replacements for the UltraLow ESR electrolytic capacitors of those years.

Regarding two-pole frequency compensation of the PWM controller error amplifier for a specific type of capacitor.
In real conditions, it does not work, and all developers limit themselves to single-pole compensation.
Try to calculate it yourself using the datasheet you provided.
The first problem is that the frequency of the second pole is outside the operating range of the electrolytic capacitor.
If we try to take into account the influence of the MLCC bypass bulk capacitor, they have a wild dependence of capacitance on voltage and temperature.

Therefore, when replacing capacitors on motherboards from those years, it is sufficient to use polymer capacitors with a capacity no more than 2-3 times smaller.
The main thing is that the total ESR and permissible current are not worse.

Aopen MX3S, PIII-S Tualatin 1133, Radeon 9800Pro@XT BIOS, Audigy 4 SB0610
JetWay K8T8AS, Athlon DH-E6 3000+, Radeon HD2600Pro AGP, Audigy 2 Value SB0400
Gigabyte Ga-k8n51gmf, Turion64 ML-30@2.2GHz , Radeon X800GTO PL16, Diamond monster sound MX300

Reply 11 of 13, by kupa97

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So the ESR of the caps I ordered for the bulk output filter capacitors (APSG160ELL152MJ16S) have an ESR of 0.008 ohms, the originals I believe are 0.013 ohms. Would this cause any voltage regulation issues?

Reply 12 of 13, by Lostdotfish

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kupa97 wrote on 2025-11-25, 19:22:

So the ESR of the caps I ordered for the bulk output filter capacitors (APSG160ELL152MJ16S) have an ESR of 0.008 ohms, the originals I believe are 0.013 ohms. Would this cause any voltage regulation issues?

Over thinking it.

Buy polymers
Install polymers
Enjoy polymers

Reply 13 of 13, by kupa97

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Alrighty, thanks.