Reveal.IT – Faulty capacitors on Presario SR5120AN motherboard

Last night, when I was swapping out the Corsair HX650W power supply from my Compaq Presario SR5120AN desktop computer to use in my VMware server, I noticed a bad or failed capacitor.  So, you might ask – what are the obvious signs of a failed or failing capacitor that it is possible to see with the eye? Here is a photo of the motherboard that I removed from the desktop this morning.


The electrolytic capacitors that quite often fail are those with aluminium cans – these are the common types that fail due to over-heating.  What happens is that the dielectric material inside the capacitor is an electrolyte that will dry out either with time or through over-heating causing vents to open.  The venting of capacitors can occasionally be an explosive event with a loud bang – if anyone is around to here it.  Sometimes if you are lucky – you might hear a fizzle.  Can anyone with sharp eyes see anything unusual on the motherboard?

Sounds of suspense here – tick tock tick tock…  Ok, see that there is one capacitor on the top left – which has a bulged and blackened top, then another four in a row beneath the cpu?  Usual signs are bulging of the top – a sign of over-pressure caused by over-heating. If the vent opens, then electrolyte is released – this is that black stuff.  The bulging with or without dark/black discolouration is how a bad or failed capacitor will ““self. On the top of the other capacitors, you can see something like a cross or a T shaped logo – this logo is actually the vent, where the aluminium is deliberately weakened so that failure occurs along the crease marks.  These capacitors are 1800uF 6.3V rated up to 105 degrees Celsius.  There are another four of these that would appear to be intact on this motherboard.  I don’t have any of these in my parts stock so will need to order.

Usually we would replace all of the ones that fail and including those of the same brand and type that have not failed, so I will need nine of them to be ordered.  I don’t have to replace the other four as they haven’t yet appeared to fail, but generally speaking, it is just a matter of time – so best to get the hard work done now instead of doing it again later. Why hard work? Motherboards are multi-layered board that can be very difficult to work on even with specialized desoldering equipment.  Sometimes no matter what, a capacitor may stubbornly resist being desoldered – and usually when this happens, we have to get the cutters out and cut it off the board, then use a soldering iron on one side of the board and desoldering iron/tool on the other side.  I have had to do this once or twice.

You may also notice that I had removed the cpu heatsink.  The thermal material has gotten quite old and is brittle and flaking off – I have cleaned it off and put in Arctic Silver 5. Then reinstalled the motherboard since it is still working, with the occasional freeze and blue screen – I am typing this right now on that desktop.  Anyway, that’s it for now.

[Note]  Desoldering equipment should be maintained regularly.  Due to the higher temperatures involved, the desoldering tip can go black from oxidation and then it will not transfer heat well, which requires increasing the temperature, which makes it worse, etc, etc.  I use a Chemtools Tip Tinner – it is something that has powdered flux and solder that reactivates the desoldering tip – also used for soldering irons.

[Note2]  When the electrolyte dries out, the capacitor’s capacitance will be reduced – which means that its function in the circuit, for reducing ripple, will be degraded.  Also the drying electrolyte will have a higher ESR (Equivalent Series Resistance).  This higher ESR also causes the capacitor to dissipate more power which leads to more heating – this is the mechanism that means that once it starts, it will continue until failure.  I have an ESR meter and with this I could test the other four capacitors to see if they are still functioning well – and then decide to replace or not, but the five failed ones definitely require replacement.

Replace.IT – FSP Aurum Pro 1000W Power Supply with Corsair HX650W

The last day and a half was quiet as our internet had been capped until this morning. During that time I have been having a struggle with the FSP Aurum Pro 1000W power supply unit that I installed into my new VMware ESXi 5.5U2 server.  I was using the VMware OVF Tool to export virtual machines from my old server to the new server and large machines would take a long time to copy – so I left it running overnight.  I was finding that the new server would be off.

It seems that after running for a time the power supply shuts down.  I remembered that I had faced this problem before during my cryptomining phase, but now I am not running that sort of power – my power meter indicates that power consumption of the new server is only 120W – low enough that the power supply should be able to handle it with ease. Unfortunately, that is not the case – it kept tripping out.  I know that it has tripped because the power button on the case does nothing until the switch on the power supply is turned off then turned on after a few seconds.

This power supply had been working so what has changed.  Then I had a hunch – the power supply also has two dedicated fan connectors for attaching fans – I do have a couple of fans on one of those cables – could they be the cause of the problem.

The Antec 1100 case has a fan power hub, that takes a molex connection and spreads it out to four 3-pin fan power connectors allowing additional case fans to be run.  I disconnected those fan cables and the power supply started running consistently.  That is until I thought I would test whether the fan cable can handle just one fan – I connected a single fan while everything was running and immediately – everything off.

Bad move!  After doing this, no matter what I did, removed all fans, removed the modular cables going to the dvd drive and the hard disks, leaving only the motherboard connected – the power supply was not going to work this time.  After resetting the power supply, press the case power button – the cpu fan would start spinning, then everything stops.  It happened more than 10 times in a row last night so I was ready to just throw the FSP power supply into the pool.  After calming down a little – I decided to “” with my Corsair HX650W power supply that I have in my Compaq Presario desktop.

I got out the original Compaq power supply from the Presario that I had put into the Corsair box – it was a 300W unit.  I had bought the replacement as I had previously upgraded to a nVidia 8800GT graphics card that needed more power, but have seen gone to an AMD Radeon 7850 which uses less power.  I removed the Corsair power supply – ever notice how much dust computers accumulate?  Also noticed a blown capacitor on the motherboard – that might explain the occasional blue screen that I had been getting recently – another story.

Now with the Corsair HX650W installed in the server – it powers up and I am happy to continue with my exporting and importing of virtual machines.

One thing that I do think of, is because of the multiple times that VMware has crashed due to the power supply shutdown – some of the data on the hard disk could be corrupted.  I don’t have a battery backup for the Adaptec 5805 array controller so any data that is going to the hard disk will not be stored.  It might be a good idea to buy the battery – it is about $150 or so and would allow data to be stored in the array controller cache then written to the disks on the next power up.  Also the Corsair power supply being a professional series – has a 7 year warranty, I will need to find the receipt and keep it handy, just in case.

[Note] Due to the multiple unintentional shutdowns, it might also be a good idea to reinstall the VMware ESXi to ensure that all the data is valid – I might do this after I get the battery and enable all the write caching, now that I have a good reliable power supply in the server.

Repair.IT of course – Corsair H100i liquid cooling standoff

There is a kit from Corsair that would contain the standoffs that we could use to replace the one that broke.  We checked a couple of computer shops but these were not in stock, with no information about when the kit might be available.

The results are in – the majority of votes (being one) are to “” – great, another use for my machinery.

Alright – lets get into it.  The standoff that had the screw stud snap off, has a M3 thread, i.e. metric 3mm thread.  I happened to have M3 machine screws in my cupboard of different lengths.  I chose to use a 20mm machine screw.  First thing is to put the standoff in my lathe chuck, then face it off.


Face off in metalworking terms means to make the end face flat, i.e. remove the remaining threaded portion.  Next, I use a 2mm centre drill – to start a hole in the end face.  A centre drill is used to put a starting hole exactly in the centre – as it means.  If I start with the 2.5mm drill that I will require, I may end up with an off-centre hole.  After doing this, I followed up with the 2.5mm drill that was needed.  To work out what hole is needed to tap a particular size thread, we refer to a tapping chart.  To tap a M3 thread, I needed to drill a hole that is 2.5mm in diameter.  Actually a 2.46mm drill would be ideal – but these don’t exist, hence the nearest one being 2.5mm.


The above photo shows the standoff after tapping.  I use cutting fluid on the tap as I am tapping, backing off from time to time as recommended.  After tapping is completed, it is necessary to clean the tapped hole – I use a duster spray on a thin nozzle to blow out the metals bits.  Next step – to screw my M3 machine screw into the tapped hole.


Now I cut the end off with a hacksaw, the length needed is not so important as long as it is similar to the original – it does not have to be exact.


Then the end is cleaned up with a metal file.  I try a M3 nut to make sure that the threads will engage without difficulty.


This photo shows the two side by side, the repaired standoff is on the right – you can see the different silvery screw.  Yes, the one on the left – the bottom thread appears slightly bent because it is – it shouldn’t be that way though, but I won’t try to straighten it.  Great – I have ““.  Overall time it took – about 20 minutes because I did not want to rush.

[Note]  When using metalworking machinery – it is always important to be safe.  Wear eye protection – the little bits of metal can be so small that you might need a magnifying glass to see them, especially when spraying into the tapped hole.  My lathe does not have a very low speed, the minimum speed is 100rpm, which is a bit too high, so it is necessary to tap manually.  I disconnect the power plug to the lathe, then install a spindle handle so that I can manually turn the chuck that is holding the standoff – in this manner, I can hold the tap handle in my right hand and turn the chuck with the left.  When working manually on machines like this, it is so easy to forget what you are doing and accidentally hit the power button – often with disastrous results.

Return.IT or Repair.IT – that is the question for the Corsair H100i liquid cooling kit

My younger son is building his first computer.  Previously he had either store bought computers or the last one was built by his older brother.  Now embarking on his journey he has specified a list of parts which were ordered and which I picked up yesterday afternoon.

The cooling system for the Intel i5 cpu that he chose was a Corsair H100i Liquid Cooler. Fitting the cooler to the motherboard comprises of installing a bracket under the cpu socket, then fitting some standoffs onto the bracket.  The cooling system heatsink is then placed on top of the cpu and then another bracket clips over the top onto the standoffs, and fastened into place with thumbscrews.

I had gone out in the evening to play badminton and when I returned, my son said he broke something.  It turns out that when fastening the thumbscrews, one of thumbscrews broke off on the standoff.


This morning I made a call to the shop and spoke to customer service.  It seems that I will have to bring the cooling kit back to the shop – they will send it away to the manufacturer and see whether or not the manufacturer will accept it as a warranty claim.  It will mean that my son will have to use the Intel stock heatsink and fan until such time as this cooling kit is resolved.  If Corsair won’t accept it as a warranty claim, then we may be up for more expenses – unknown at this stage.  I checked that there is available a Corsair Intel Mounting Bracket Kit for this cooling system that would contain all the parts needed to install it – specifically, it contains a set of standoffs – for $18.70.

After inspection of the standoff, I determined that the broken screw thread is a metric 3mm thread.  It would be possible to face off the standoff, drill a 2.5mm hole into it, then thread it with a metric 3mm tap – then insert a M3 screw and cut it to length.

The question then is… “Return.IT” or “Repair.IT” or buy the kit?

What do you think?

Another alternative is to email Corsair and ask them if they would consider this as a warranty claim and if they can just send out the replacement standoff.

[PS]  The Corsair warranty indicates that within the first 30 days of purchase, to return to the place of purchase – after that to contact Corsair in HK.