Expensive Graphics card - smd caps literally on fire - Page 1
Forum section: electronics / general

author: xtv
author_rank: Contributor
timestamp: May 05, 2014, 03:42:00 am
content: Ok, so I have this happening before. The computer PSU shuts down out of nowhere.As this is in an open case, when I power it back on, I literally see something getting fire on this graphics card!At the first time, I obviously thought I've lost it, but for my surprise, the computer booted up and the card was running normally at full trottle.Days have passed, I had powered the computer down and up several times, and then the above happens again.After powering on, I noted that something got on fire again, so I powered it off and took the card out. Examined it, but couldn't find anything visibly toasted.Reinstalled it, the card was still working fine.Days have passed and then the unexpected shutdown again. Power on, fire on the graphics card!At the last time, when I powered it on something got on fire in the graphics card, it was up for a couple of seconds, and then the PSU shutted down.Took the card out and for my surprise, when I remove the secondary heatsink (photos), I saw 4 smd caps totally toasted.They seem to be part of the DC-DC converter. These card's GPU works around 1-1.2v, at very high loads (reaching over 100A).I'm not experienced with DC-DC converters, but this caps could only be on fire due to a high overvoltage, right?Does anyone have a theory about how this can be happening? What should I do?Images: (click on the large image for better zoom)Datasheets:4C05Nhttp://www.datasheetarchive.com/dl/Datasheets-D6/DSAHI000109721.pdf4C10Nhttp://www.datasheetarchive.com/dl/Datasheets-D6/DSAHI000109725.pdfNCP5369http://www.onsemi.com/pub_link/Collateral/NCP5369-D.PDFNCP4200 (couldn't find NCP4206's)http://www.alldatasheet.com/datasheet-pdf/pdf/315763/ONSEMI/NCP4200.html

author: miguelvp
author_rank: Super Contributor
timestamp: May 05, 2014, 06:27:08 am
content: Quote from: 3roomlab on May 05, 2014, 06:25:42 amI was going to say video toaster

author: Psi
author_rank: Super Contributor
timestamp: May 05, 2014, 07:02:07 am
content: Sounds more like the wrong part was placed on the PCB and they didn't bother testing the batch before shipping.They look ceramic but i guess they could be tantalums with the wrong polarity, that would certainly make them quite unhappy.Check the manufactures website, maybe there's a recall or something.

author: peter.mitchell
author_rank: Super Contributor
timestamp: May 05, 2014, 07:26:58 am
content: If they are under a heatsink (even with a sil pad), thermal cycling can cause mechanical stresses, leading to internal fractures and short circuits.The heatsink was probably slightly over tightened during initial assembly.

author: poorchava
author_rank: Super Contributor
timestamp: May 05, 2014, 07:59:35 am
content: Ceramic caps have very low ESR and they can handle impressive ripple currents, but they are mechanically very fragile. I would bet on cause being thermal cycling or improper reflow parameters during assembly.

author: tszaboo
author_rank: Super Contributor
timestamp: May 05, 2014, 10:03:32 am
content: Is it under warranty? IF not, I would still knock on their door.

author: SArepairman
author_rank: Frequent Contributor
timestamp: May 05, 2014, 10:05:48 am
content: i think he might need to use the "ring trick" to get them to open the door for him... are they really that nice?bonus points to who figures out the reference

author: Psi
author_rank: Super Contributor
timestamp: May 05, 2014, 10:32:52 am
content: Manufactures are usually happy to help people who bought their really high end cards.It's a small fraction of their sales but a high profit area, so it doesn't take a lot of their time and keeps the people happy who are spending the big bucks.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: May 05, 2014, 02:56:26 pm
content: I had a computer that went down one day. Everything was working fine, and then "blink", all off and wouldn't turn back on. Tried the power supply on the bench, nothing. Swapped the power supply for a known good one, nothing. I figured the PS blew and took out the motherboard with it.So, I built a new machine, all new parts from the ground up. I got it up and running, and then installed one of the hard drives from the original system to see if I could pull the data off of it. I turned on the power, BIOS posted, and then it just froze. After a few seconds I peeked my head around the edge of the tower, and saw that the hard drive I had just plugged in (the one from the dead machine) was on fire with about 4" flames coming off of it.My best guess is the old power supply, when it failed, sent a voltage spike through the system which fried everything in the machine, motherboard, hard drives, etc. It must have killed the hard drive in such a way that it caused the dc/dc converter on the drive to short itself out. As soon as I plugged the hard drive into a good power supply, short circuit = fire.The point is, just because the video card fried, doesn't necessarily mean the video card is at fault.

author: xtv
author_rank: Contributor
timestamp: May 05, 2014, 03:03:41 pm
content: Quote from: 3roomlab on May 05, 2014, 06:25:42 amThis is a R9 280X card, with AMD GPU, "manufactured" by Sapphire..

author: xtv
author_rank: Contributor
timestamp: May 05, 2014, 03:29:04 pm
content: Quote from: peter.mitchell on May 05, 2014, 07:26:58 amWhat I can think now is, the cap gets short circuited. PSU shuts down due to OC protection. On power-up, OC protection is disabled for a very short period, but enough to fry the in-short capacitor.Question is, is it possible for this cap (looks ceramical, have no polarity marking afaik) to get in short circuit?This is still very strange to me... Suppose the capacitor could get in short due to physical changes. This couldn't happend in a fraction of seconds. If this could happen gradually, the rails in the card have proven to be powerful enough to be blowing any attempt of getting in short circuit inside this component..

author: xtv
author_rank: Contributor
timestamp: May 05, 2014, 03:41:39 pm
content: Quote from: suicidaleggroll on May 05, 2014, 02:56:26 pmNow that is fire!I wouldn't blame the PSU this time though, for the following reasons:- I have 3 more identical cards running in this same machine. None had a problem. This one being the match head for four straight times comes to be unlikely;- Semiconductors are much more prone to get damaged under voltage variations than a ceramic cap. Specially if this was caused by a spike. Like in your hard drive, looks like you have a well blown silicon wafer in that smaller microprocessor..- Anything else in the machine didn't get any damage (so far)

author: xtv
author_rank: Contributor
timestamp: May 05, 2014, 03:52:16 pm
content: Quote from: Psi on May 05, 2014, 10:32:52 amI'd be happy to agree with you, but my experiences are somehow different.. I've mailed them asking for replacement fans for this card, as they're dying after 3 months of use. No, they don't do that. I've instead mail them the card and wait for a couple of months to possibly get it repaired.BTW, it's unbelievable how crappy are the fans they use on a product supposed to be high end.Maybe that could happend in smaller companies though, when things are less "corporation" and more personal.

author: lpc32
author_rank: Frequent Contributor
timestamp: May 05, 2014, 04:12:21 pm
content: Quote from: suicidaleggroll on May 05, 2014, 02:56:26 pmWhat was the PSU brand/model? I want to know what to avoid.Or were there any extenuating circumstances?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: May 05, 2014, 05:49:16 pm
content: Quote from: lpc32 on May 05, 2014, 04:12:21 pmNo extenuating circumstances, no thunderstoms or small children with screwdrivers. It wasn't even doing anything processor or power-intensive, just quietly idling in the background.This was many years ago (if you notice the HDD is PATA), and I don't remember the make of the PS anymore. It was a name brand though, Antec was my go-to at the time, so there's a good chance that's what it was. The system was built ca. 2005, and this failure occurred around 2007, so it was somewhere around 2 years old at the time.

author: daveshah
author_rank: Unknown
timestamp: May 05, 2014, 05:50:39 pm
content: Quote from: xtv on May 05, 2014, 03:03:41 pmWasn't this released last October, therefore isn't it still under warranty?

author: lpc32
author_rank: Frequent Contributor
timestamp: May 05, 2014, 06:17:26 pm
content: Quote from: suicidaleggroll on May 05, 2014, 05:49:16 pmDisturbing.

author: xtv
author_rank: Contributor
timestamp: May 05, 2014, 10:09:20 pm
content: Quote from: daveshah on May 05, 2014, 05:50:39 pmIt is, the card have 4 months old in my hands.I bought it overseas, so it will take some time to be replaced, with some risks, but I guess I'll do it.

author: peter.mitchell
author_rank: Super Contributor
timestamp: May 05, 2014, 11:48:24 pm
content: Quote from: xtv on May 05, 2014, 03:29:04 pmYes, the most common failure mode of MLCC is low DC resistance (eg, short circuit), the second most being a significant decrease in capacitance.Generally it is a mid to long term process with an avalanche presentation - the mechanical and thermal stresses continually weaken the ceramic structure over a long time, until all of a sudden, it breaks, if it breaks it can fail short circuit.As you suggested, when a PSU is first turned on, OCP is disabled for a short period, this is because as the DC voltage is applied across a lot of empty capacitors, initially, these look like a short circuit as they charge, until they no longer take any more charge, at which point they appear open circuit.

author: xtv
author_rank: Contributor
timestamp: May 06, 2014, 10:24:08 pm
content: Quote from: peter.mitchell on May 05, 2014, 11:48:24 pmGood talking to someone experienced. I wouldn't imagine a common failure of these MLC Capacitors is low resistance..I've checked and these small SMDs are wired in parallel with the solid capacitors near them. They're 10 uF and I'm guessing they're there to hold some ripple (maybe from the inductors?)I'll take these caps out and check them..I'll see if I can find other caps for replacement..PS: Just an off-topic comment, but working in these lead-free boards is quite a pain!I don't have a proper soldering station.. I have one 30W and one 60W soldering irons, and even working with the 60W that gets quite hot, it's pretty hard to melt the stain in the board..I didn't get a soldering station yet because most of them (the affordable ones) doesn't contain a powerful enough soldering iron, so I guess it'll be a waste of money..

author: peter.mitchell
author_rank: Super Contributor
timestamp: May 07, 2014, 01:58:47 pm
content: It's not so much the lead-free, it's the board itself, i'd guess its probably an 8 layer board with massive copper pours - you're essentially soldering to a heatsink.Another reason they may fail short is dielectric breakdown from overvoltage, and knowing of your issues with your power supply, this could possibly be the case.The caps are on the input to the FET+Drivers, they see 12V, with up to 1Mhz~, high current draw spikes, they look to be 0603, probably X7R. No idea what value, probably 1-4.7uF. Probably only rated for 16v Would have to desolder a good one and check, though, probably not vital the value.A good sign is, none of the output caps seem to have popped, so thats something you've got going for youI gotta say though, If you want to know from a real expert in this field, ask @TiN , although he's probably quite busy with other things.