Asus A7V8X hdd issue

[Baddflash]

Just wanted to share a strange issue I was having when trying to get this system running again. It was working perfectly fine when put away.
A7V8X r2.01 XP2500(@2200mhz)+ 2gb DDR 400, AIW 9600xt 128mg, Audigy, Pioneer DVD-105 , DVR-115, Maxtor 300gb, seagate 160gb, Enermax Tomahawk 405w

A few years later when trying to get the system up and running again I could not get it to boot with two hdd's connected no matter how I set them up. Master or slave IDE 1 or 2, I couldn't even get the seagate drive to detect by itself after awhile, however with just the Maxtor and dvd drives it would boot to either XP or 98 without issues.
Because with just the two hdd's connected both would fail to spin up properly I initially thought the psu was at fault, however the same issue was there with a known good psu, and the psu caps tested fine.
All the caps on mb appeared ok on visual inspection however after removing to test I found the 3300uf 6.3v KZG all read around 5300uf and the 1500uf 6.3v KZE were reading around 2000uf.
Decided to replace them all with some Nichicon HD and HW I had on hand and all is well.I just thought the symptoms were strange and maybe it would help someone out to know what my solution was.

[bigbeark]

Re: Asus A7V8X hdd issue

I assume they were NOT bulged or leaking?

[RJARRRPCGP]

Re: Asus A7V8X hdd issue

IIRC, I had a 2003-made A7V8X-X (Via KT400) with a green KZE cap and Ost caps.

On their later nForce 2 versions, (A7N8X) Asus seems to love using KZGs. Asus may have been using Nichicon HMs on their earlier A7N8Xs more often.

On my 2004-made Asus A7N8X-X, KZGs all over with Ost caps around the AGP slot, PCI slots and RAM slots.

[momaka]

Re: Asus A7V8X hdd issue

All the caps on mb appeared ok on visual inspection however after removing to test I found the 3300uf 6.3v KZG all read around 5300uf and the 1500uf 6.3v KZE were reading around 2000uf.

Yup, that's a classic failure mode for KZG, especially those 3300 uF ones: capacity goes through the roof and much higher than the 20% allowable spec. This is a sign that the capacitor electrolyte is breaking down and "eating" through the foil plates, thus increasing capacitance at the expense of the cap able to withstand lower voltage and becoming more electrically leaky. In time, this progresses to the point where the cap will eventually vent.

So the short story really is: if you see 6.3V 3300 uF United Chemicon KZG series, replace them without question - especially on old hardware like this.

Now as for the 1500 uF KZE reading around 2000 uF... are you sure those were indeed KZE series and not KZG again? KZE are actually very reliable series, so I would be surprised to see these have failed... or at least starting to read high capacitance. What device did you use to measure the capacitance of these caps? Whatever it is, I'm sure it actually measured the KZG correctly as failing. But just want to confirm if that can also be said about the KZE.

Decided to replace them all with some Nichicon HD and HW I had on hand and all is well.I just thought the symptoms were strange and maybe it would help someone out to know what my solution was.

Bad caps can cause absolutely *any* sorts of issues - from BSODs and no POST, to intermittent crashes, to very very specific things not working (like HDDs not powering up, not all RAM sticks getting detected, crashes in specific software scenarios, and so on.) So if you see any, don't expect the issues to be bound to only once certain area of the PC - they can still affect the operation of other circuits in the PC too.

On that note, also check your Enermax Tomahawk PSU for bad caps. Enermax really liked to use CTC/PCE-Tur/Tuk/Tuv caps in many of their older PSUs, many of which went bad eventually.

[Baddflash]

Re: Asus A7V8X hdd issue

None of the capacitors had any visible signs of issues at all.


Yes the 1500uf in the mainboard were KZE as were the 1000uf caps in the psu but all those ones tested perfect. The ones on the mainboard are the right age and given the state of the other ones it doesn’t surprise me they were bad too.

The computer has been working flawlessly since recapping.

[Wester547]

Re: Asus A7V8X hdd issue

So this may sound like a ludicrous question, but I’m guessing you did measure every single capacitor, including the PSU capacitors, out of circuit, to determine whether or not they measured to spec? Because you can’t get accurate measurements in circuit due to capacitors being in parallel or series with other components. And I’m also guessing you waited until the capacitors cooled down if you did measure them out of circuit once desoldered as the higher temperatures from the thermal output of the soldering iron could result in higher capacitance readings, especially in the case of the KZE (despite using an aqueous electrolyte with a moderate amount of water; KZGs are comparatively high water content capacitors, and based on the case sizes, they also have a thinner oxide layer). KZGs, especially the elder ones and especially the 3300uF 6.3V variants, need no reason to fail. The manner in which the KZE failed (high capacitance like all “plague” capacitors), on the other hand, I consider to be a bit worrying. I always thought them to be a reliable series even if this instance was a “one off” (although more likely a “wear out” or “heat-related” failure this far into the life of the capacitors).