Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

[themadcapper]

I'm looking to recap several SuperMicro P3TDDR motherboards, as the NSRY 1000uF 10V 105degC capacitors all seem to be going bad. Some are bulging, some appear to have slightly leaked. Now here's the big question. I checked all these seemingly bad caps with a Bob Parker ESR meter, and even the seemingly bad ones are showing 0.03 to 0.04 ohms or so. So, does this mean that they are really okay, or is it possible that they are failing once under the strain of heat, etc. Note that all these boards still post, boot, etc. They just intermittently reboot, and I can only seem to trace it back to this capacitor issue. The next thing is that I got a deal on a huge bag of QVS 1000uF 10V QZR 105degC capacitors to use as replacements. But, ironically, these caps seem to have an ESR of 0.08-0.10, nearly double the NSRY caps used.

So, the question is, can the QVS caps be used to replace the NSRY caps, or is that ESR difference simply too much, and can all these seemingly bad caps still give good ESR readings on an unpowered motherboard at room temperature?

I read all the FAQs and unless I missed it I couldn't find any direct references to this particular issue.

Appreciate any help you all can offer! :-)

[kc8adu]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

never heard of those qvs caps.post a pic.they are probably not high quality low esr.
i use panasonic fm 1500@6.3 on those boards.
you are likely measuring several good ones in paralel with the bad ones.
recapping has fixed every one of the p3t boards i have done.

[starfury1]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

just to expand a bit on KC8 said

you are likely measuring several good ones in paralel with the bad ones.

Assuming you measured them while in the pcb

Now bear in mind, ESR for the sake of simplicity is like a resistor

So if you have say a 10 ohm resistor in parallel with a 2 ohm resistor the total resistance would be still less then 2 ohms so you wont see the 10 ohm resistor.
ditto the caps ESR
so to be sure you need to remove and measure each one.

As to if they fail under heat etc "yes"
the ESR will go higher as it gets hotter (normally with good caps)
so the lower the ESR the better
(thats if I understand it right)

since you say some are bulged etc ..they are history

you should replace all caps in the VRM if you want max life out of them and it

Since they are all still working "now" would be a good time to recap them

As to those caps well if they measure cold, higher then the ones in there I wouldn't use them...go with the Panasonic FM as KC8 said
(I think you would just be replacing trouble with more trouble but thats only my opinion not the guru here)
VRM circuit is not really a place you want to try and cut any corners on I think

I've never heard mention (that I recall) of those caps either.

HTH cheers

[themadcapper]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

That definitely sounds like the case then - they do always tend to be grouped together. But, thinking about that.. wouldn't it be then nearly impossible to ever detect bad capacitors still on the motherboard due to that very issue? It seems like they'd have to be taken out regardless to accurately test them. Regarding the Panasonics, so you're saying it's okay to change them to the higher 1500uF at the low 6.3V instead? I did see something about that in one of the FAQs. Is there any advantage to using lower voltage/higher uF caps? Do they tend to last longer? Also, where do you generally order your caps for the best prices? I also included a picture from the bag of caps I got ahold of on ebay - there are 500 of these babies in the bag. It's ashame that it sounds likely I won't be able to use them though.

Thank you both btw for your excellent advice!

[kc8adu]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

i will have to hunt around for a datasheet on the q caps.
i went to the 1500@6.3 due to unaceptable(to me) hash on vcore.
highest voltage these 10v parts see on a mobo is 5v.
vcore is1.4?

[themadcapper]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

Actually, the vcore's on these motherboards are 1.7 V. Also, what do you mean by the hash on vcore? Is that like the ripple current? Also, what kind of scope do you need to check those stats (ie Mghz, etc)? Would something like the osziFOX work (https://cdn.badcaps-static.com/pdfs/...ac761080af.pdf)?

[gdement]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

That definitely sounds like the case then - they do always tend to be grouped together. But, thinking about that.. wouldn't it be then nearly impossible to ever detect bad capacitors still on the motherboard due to that very issue? It seems like they'd have to be taken out regardless to accurately test them.

That is a problem, and this is why I think accuracy does matter with ESR meters. If you're measuring only 1 cap then a bad one will stick out with an obvoius, very bad reading. But since the important caps are always going to be in parallel, a bad bank of caps might still only show a moderate reading. And if any of the caps are still in good condition then the reading might look close to normal in circuit.

For this reason, I'd be suspicious if the circuit's ESR is even slightly higher than normally expected. The Vcore circuit on most motherboards usually reads 0.01ohms on my meter, so if I found 0.03 at Vcore I'd be swapping them out.

It can help to know which caps are in parallel with each other, as this gives you an idea of how low the ESR should be on that circuit.

[starfury1]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

Well I'll let KC8 answer for himself on that,
cause me don't really know, I think he means noise, ripple voltage, garbage at unacceptable level to him.
(this maybe possibly caused by higher ESR)

I really don't know enough to get into the detail of what causes what at what temp or current, frequency etc.

Not in regard to what you have (with the caps) but generally speaking and my understanding is the reason you may find lesser quality caps fitted at 10 Volts is the ESR is less for a higher voltage caps, this allows them to use lower quality
(read as cheaper) to run the VRM circuit with.
This does not mean they will last as long as a good quality cap or have optimal performance for where they are used

My guess is you are only or most likely only find low ESR quality caps at 6.3 volt (or 16V)
Since the circuit will not require any more then this you can use them cause there voltage rating is not going to be exceeded.

The whole thing can get quite complex and there are a few discussions threads on all of this.

Kc8 by the sounds of it has done some investigative work on it and has given a recommendation of a cap that should be quite suitable to the task and from his experience works with the MB's (and works probably quite well)

This is not saying what you got wont work and last for a period of time,
just my personal thoughts are it wont last as long as the panasonic FM would
BUT this really does depend on quality of the QVS cap I suppose.
(but being spec @10V and Higher ESR doesn't sound good for this application)

I cant seem to find data on them
the only site I found with a logo similar
Was QVS discount Electrical wholesale...no electrolytic capacitors listed
(as far as I could find)

http://www.qvsdirect.com/

could find no PDF's specs either?

so I dont know what they are or who actually made them.

As to having to pull each cap...well yeah yes if you want to be sure
(the above post is the theory of it)
Normally the best way to test a component is to remove it from circuit.

Here again if you find 2 or 3 popped etc, its really a must anyway to replace the lot
(so you don't need to bother testing the caps just recap)

Anyway the choice on caps is yours, and I can understand why your are considering the caps

me personally would use the FM's
There are better caps but bangs per buck they are good value

heres the pdf link if you want to have a look Panasonic FM PDF

HTH Cheers

[starfury1]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

ok I stand corrected the FM do have a 10 Volt in the pdf...
I think its RS components just has 6V3 16V listed for low ESR caps
more often then 10 V (if any?)

this maybe the case with a few suppliers I guess

[themadcapper]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

Here's an interesting update. I just took off one of the bad looking NSRY caps from the motherboard, and the ESR meter immediately showed around 1.5 ohms. Each time I would try again it would edge up and seemed to settle (for now) around 2.8 ohms - kind of weird, but definitely a bad cap! Now here's what's really odd. I compared again to the QVS caps I have. When I measure them right from the base of the capacitor (as opposed to from the ends of the wires) I'm actually showing an ESR as low as .04 to .05 ohms!! When I measure from the end of the cap's leads, I'm getting closer to .09 ohms or so. How does that make sense? Maybe I'm introducing some noise or something holding the leads to the meter probes. Strange, but either way whether it's .05 or .10, 2.6 ohms is definitely a far cry from a good cap!

On a separate issue, one thing I am still curious about is why they put the caps in parallel as opposed to using one bigger cap. Does that add some extra degree of reliability? It doesn't seem it would because in the end if one goes bad it's still screwing the rest of them. Maybe it's just so they don't need to stick one big one as opposed to a few little ones?

[gonzo0815]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

0,05ohm is not that bad, actually many even good quality PSU caps have esr as high as 0.068ohms per 1000uF.

Any way, in your case it is obviously a badcap problem ;-)

Adding caps in parallel is to lower the esr further.
And sure, it is probably a better approach then using very few ultra lowest esr caps which are in most cases not that durable then the other series.
Imagine those very high currents a modern VRM has to provide, e.g. 55A (sure, only for a very short time) for a soket A CPU and probably a little more for some Intel ones.
At such high currents, even a very low esr would cause a significant voltage drop and poor regulation.

[themadcapper]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

Just wanted to let you all know that I've now used the QVR caps to replace about 35 bad caps over three P3TDDR boards so far with great success (I've got about a dozen of these machines)! One of the boards just konked out yesterday... It wouldn't even post anymore. After the recapping, it's running beautifully again - hasn't even flinched! Some of the bad caps I pulled off were at 4 ohms or more, some that were starting to go bad may have been about .75 to 1 ohm or so. I don't know how great the quality of these new caps are, but they certainly seem to work for now! I got the technique down pretty well so I can chug along right through the process, so it wouldn't be a big deal to fix it again even if some start to go bad down the road (2 years + maybe?!) The important part is I now know the nemesis that's plagued me for a while with these - just in time! Amazing how these companies - even big "quality" server companies like SuperMicro - build in "planned obsolescence"! Luckily for us they decided to go cheap on the only parts of the motherboard that are relatively easy to replace!

Thanks again for all of your help! I'm going to be making an episode of our internet shows on this topic (www.vlogolution.com - youtube:vlogolution) - this forum will certainly be mentioned as a prime source of data on the topic...

[pc-mike]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

Hi themadcapper:

I don't know if you are still on this forum, but you mentioned you have several servers with Supermicro P3tDDR motherboards. If you ever do upgrade those machines, I have a customer who is running a (legacy) server that had that same P3tDDR motherboard and who would be interested in purchasing either a spare motherboard or a whole spare server with that motherboard in it. Let me know if you want to sell one. mschw@athenet.net

[Logistics]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

I know... FORUM NECROMANCY! But I run a P3TDEI and at the moment it has a 1.45 Vcore with the 1.26GHz-S Tualatins, and I noticed most of the CPU's in the PIII line, except for the Tualatins, depending on their speed, have different Vcores throughout. So I don't know where that 1.7V Vcore which was mentioned earlier came from.

I'm considering selling one of my P3TDEi 1U racks with dual Tualatin 1.26-S's, but I want to polymod my dual 1.4-S just for fun. I'll post a thread when I get to that.

[Th3_uN1Qu3]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

but I want to polymod my dual 1.4-S just for fun. I'll post a thread when I get to that.

Heh, me too. Only i'm running an ASUS CUV4X-DLS - i need that AGP slot so a server board was out of the question.

[Topcat]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

P3TDDE with a pair of 1.4GHz Tualatin-S's.....8x AGP. I didn't polymod it, just recapped the taicon lytics that it had, never had any trouble out of it.

[Th3_uN1Qu3]

Re: Recap Help with P3TDDR motherboard - bad cap ESRs seem okay???

That there is a pretty nice board Topcat. Let me know if you have one for sale, as my Asus mobo has some issues with the USB, regardless whether i'm using the onboard ports or a VIA PCI USB 2.0 card, it corrupts large files. And it has nothing to do with the overclock running the PCI clock above spec, as it does the same thing at stock.

Btw, does the Supermicro board support any overclock option? I guess not, but that's not a big deal as it can likely be hacked.