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Old 02-24-2015, 02:02 PM   #13
mockingbird
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Default Re: DFI-ITOX G4S600-B with Chemicon KZGs - compatible caps?

Quote:
Originally Posted by jesscat606 View Post
overkill? I note that those are 1000uf, not 1500...is there a reason this is ok, other than that's the nearest size Digikey has? (I'm not tied to digikey, I'm just more familiar with them.)
Because when you replace VRM high caps, you usually use polymer equivalents with a much much lower capacitance. This has mainly to do with the fact that 16V polymers don't go very high in capacitance, especially at 8mm. Since yours are 10mm, I chose 1000uF to be safe, eventhough you can probably use as low as 270uF here.

The reason that you can get away with this on the VRM high, is that with the VRM high, low ESR and high ripple are important, and not bulk capacitance, or at least that's what I have been told.
Quote:
these are all 2.5v, not 6.3v. The only 1500uf/6.3v/8mm polys i saw were smd.
Pentium 4 VCore is less than 1.5V. That's why 2.5V is more than sufficient on the VRM low. If you bought 6.3V ones in 8mm, you'd just be spending a whole lot more money for no reason.
Quote:
Are there any likely problems or concerns with mixing poly/non-poly caps on a board? I like the extended life of the polys, but don't wanna cause issues.
Nope. At least not in your case.

I've done it myself. I have an Asus P5B I use almost on a daily basis. For the VRM high, I used ordinary Nichicon HM, and for the VRM low, all UCC PSC 2.5v 820uF polymer caps.
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