ASUS P5K Capacitor Mod

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Today, we will be looking at a capacitor mod of an ASUS P5K. Let me state at the outset that there is no compelling need to take the soldering iron to this board if you don’t plan on extreme overclocking or pushing a Quad to its max. Frankly, I did it because I had the time and because I wanted to give a pesky ROHS (lead-free solder process) board a shot.There is lot of conjecture and educated guesswork involved and I could not test the board with a quad-core. So, there are no quantitative or qualitative results available. This article is intended to be

Why Mod?

The motivation is to prepare this board for a quad-core CPU. There have been reports of caps blowing up with the P5K series of boards when pushing a quad-core CPU to the max. In most cases the caps that blow up are either on the CPU VRM side or on the source ATX 12V connector side.

There can be two possible reasons booth which have a cascading effect.


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  1. You may substitute the Sanyo's I used with Chemicon PSA available at digikey. If you are attempting something similar, send me a self addressed padded envelope and I'll send enough over to finish your project. :)
    Honestly, I did not have a whole lot of data to talk about so I put in as much as I knew about how things are supposed to fit it. I'm not a design engineer so there may be a few inaccuracies. I think the board is chugging along in corpsejockey's grandma's rig. :)
    Read the article as a complement to this one-->
    Quick question. I got a couple capacitors rated at 2.2F(5V) and 1F(15V). Would those be better for this?
    Also, how do I calculate ESR?

    Those are supercaps, usually for backup power on small current circuit or load transient supressor on circuit that needs sudden burst of high power, can't be used on mobo since their capacity is way too large, it would like shorting the switching output if you put them in the mobo. :D
    You can't calculate cap's esr, you need to measure it using ESR meter, lower is better and for switching power caps the good one usually within mili ohm range. And common multimeter doesn't have the ESR meter feature, usually it is a dedicated meter solely to measure ESR.
    Check their spec sheet 1st, but that only an early clue and there is no guarantee especially they're not new, used or exposed to high heat before, and caps have shelf life too. So for new old stock like the one in surplus shop, they needs to be checked if you want top performance caps.
    Very nice article. I've got the P5K premium, which has an eight phase power supply, but theres still a couple caps missing, around the ram slots. Meh. Reminds me of the Asus p4p800 droop mod days. :)
    I don't think you need to mod the P5K Premium. I have one in my lab right now. Even with the P5K, these mods are targeted at the extreme cooling crowd. If you are on air, no need to mod. Now I would fully recommend replacing garbage caps if you come across them (in any device). :)