TX750W And A Very Bad Day!

Hi All

Well today has been a day where a call to the Samaritans would not have gone a miss however I registered with the Corsair forums instead on a hope that someone at Corsair will have the common decency to offer some explanation and resolve to what has turned out to be a saga!

I will try and keep things as brief as is possible and to start with let me tell you I have just bought components for an Intel i7 based computer with Gigabyte P55A-UD5 main-board and Corsair DHX memory and of course the Corsair TX750W.

On build completion the system would power up, get so far into the boot sequence then sometimes reboot and other times shut-down. Not what I was hoping for so time for some serious diagnostics.

Unplugged all hardware and left only the PSU connected to the ma-inboard via the 24PIN ATX and 8PIN 12Volt ATX plugs to narrow the fault finding process, problem with booting was still there so suspect either faulty PSU, Main-board or CPU/memory.

Had another Motherboard to hand (Asus M4A785-M) AMD based with a 140 Sempron so used this as a test bed for the TX750W PSU and this booted fine for the first couple of goes but became erratic after several boots and the PSU would begin to fold and cycle (Yes I no a thing or to about switch-mode PSU's!)

So I am now able to replicate and prove the PSU is faulty by using alternative hardware to hook up and test the PSU. At this point I feel the problem is more severe on the i7 new build as appose to the AMD Sempron. Anyone from a technical background will have deduced and spotted that the fault is more prominent pending the load condition.

My last test was to put the PSU on two different PSU tester modules I have in the workshop, one is more of a voltage test and the other a load test device. Suffice to say the basic voltage tester brought the suspect TX750W into life with out any problems at all. The tester I call a load tester initialy worked fine so I applied additional load to the PSU by hooking up a couple of hard drives and I could now replicate the fault I described with the PSU over and over.

I mentioned I knew a thing or to about switch mode PSU's and that is because I have worked for many years as an electronics engineer repairing to component level so my knowledge always makes me wary about so called computer return/technical departments who often assume if you plug something in and it just works its ok and not faulty!!!! .... Today my fears of so called technical departments were to be justified when I tried to return the PSU as faulty.

The PSU was bought from a computer retailer in Horwich Bolton (Corsair should no who I mean as you had one of your representatives there today). The first point of contact at returns reached for a basic PSU tester, disappeared and came back to inform me the PSU was fine, I duly told him and repeated myself that the PSU fault was only apparent under load so off he went again to do more testing and he returned once again insisting the PSU was fine. Now at this point I saw red and told him in no uncertain terms that the PSU was faulty and that he was not loading the PSU enough in his test to make the fault apparent... Having got into a row I proceeded by presenting the returns chap with my own tester and the hard drives I used to load the PSU and produce the fault and after a further exchange of heated words from myself he offered to let me into the company's workshops to speak with the company's "electronics expert"... The electronics expert also tried to insist the PSU was ok and laughably suggested my PSU tester was faulty and causing the PSU to misbehave, he suggested that I had a loading resistor gone short circuit on my tester so In disbelief I tried to educate him on how resistors go faulty and fail and I think anyone with experience will agree here that resistors when faulty either go high in resistance or open circuit and not SHORT circuit as he suggested. I digress a little here but feel for the benefit of others reading the post its important to stress that in my case the retailers technical department was not to be trusted and were in-fact incompetent. Anyone without a fair technical knowledge at this stage would have wasted there time in the returns process and still have a faulty PSU.

The upshot of my visit back to the retailor today after eventually proving the PSU was faulty with a test using my own test equipment and also letting the retailor test each of my test devices for a pass was a replacement PSU however this is not the end of what has been a bad day.

Surprise surprise the replacement PSU does the same as the first hence why I am here. and it would appear from reading other user comments in the forum this is a problem that keeps surfacing!

Back to the bench with a trusty 380Watt PSU from a different manufacture and I7 rig works perfect, the AMD test rig works perfect, my PSU tester with loads works perfect so "Houston We Have A problem"

Corsair this is at the point where I feel you owe me some answers having caused me a day of complete frustration not to mention the unhappy customer I have breathing down my neck on what is still an unresolved problem.

Please don’t suggest I go back to my retailer as they are technically inadequate to grasp the technicalities of the problem and resolve it. Also it would be pointless returning the PSU to yourself for a replacement as this will put me back on the merry roundabout of despair having tried two of the same product already. If you have followed and understood my diagnostics and processes of elimination you will also appreciate a further TX750W is pointless as this product is clearly flawed and has some serious issues that should not be inherent on such a fundamental component.

Corsair I have supported your company by consistently buying your products for both system builds and upgrades and I feel it is your turn to offer some support back and assist me out of this seemingly hell hole I find myself in at the moment.

I await your satisfactory response and resolve in the hope that some form of faith can be restored in Corsair as a company and the Power Supply products it produces.

Yours sincerely

A Hunter.

I forgot to mention in my own testing its the +5 Volt rail that seems to be the culprit when the PSU acts up and starts causing boot failures and shutdowns. The +5 Volt rail on the TX750W is suppose to be able to sustain 28Amps consumption so it is a mystery why this rail goes bananas during bootup but its a problem I see over and over in the forums.

Carefull monitoring with my Digital storage Scope shows the +5Volt rail is all over the place at the point of faillure and during the boot process so obviously something has to give so we either get a reboot or shutdown. On the occaisions I have managed to monitor the + 5 volt rail in a successful boot to OS I have seen some nasty dips in the + 5 volt rail so I suspect on occaisions these dips in voltage at boot are on the edge of the point where it causes a problem which would account for why it can be erratic.

I will say it again at the risk of repeating myself but Corasir you have a serious problem here and we as end users deserve some honnesty.

Sorry for this omission from my first post which I am still awaiting a response from.

AndyBoyo

Carefull monitoring with my Digital storage Scope shows the +5Volt rail is all over the place at the point of faillure and during the boot process so obviously something has to give so we either get a reboot or shutdown. On the occaisions I have managed to monitor the + 5 volt rail in a successful boot to OS I have seen some nasty dips in the + 5 volt rail so I suspect on occaisions these dips in voltage at boot are on the edge of the point where it causes a problem which would account for why it can be erratic.

Sorry for this omission from my first post which I am still awaiting a response from.

"still"? I'm not sure how fast you're expecting a response, but the fastest way would be to call in directly @ 1-888-222-4346.

Were both in the UK, is there a number for us? or do we still phone the USA number?

Andy, please send an email to ramguy@corsair.com and include your contact and shipping information in the message along with a link to this thread. Also please put "ATT: Ramguy" in the subject line. I would like to set up a failure analysis RMA so that we can take a look at the PSU.

Ok I have sent the email but having experienced the fault with two TX750W and replicated the ugly fault on 3 totaly independant sets of hardware I am somewhat curuious how the testing will be done, it is important we are talking about the problems with more than one power supply if you include the one which has been returned to the retailer today. Also I want to remind you that all 3 test setups I have refered to in this saga are all working without a single hitch on a 380 Tagan PSU so please bare this in mind as it confirms concrete that the problems lie with the TX750W PSU

Also in a further thread down the page I detailed my findings on the +5 Volt rail being erartic during the boot process and the voltage fluctuating around a good few percent. Monitoring the +5 with a Digital Storage Scope shows two prominent places during the bootup process where this rail goes eratic and I suspect it is that these points that the PSU is on the edge of tripping and either causing a system shutdown or an instability leading to the system rebooting and falling into a process of cycling, boot, crash, boot, crash and so on.

As I see this problem re-occuring over and over again with Corsair PSU's I am curious as to wether the electronics controlling the chopper pulses along with all the feedback control etc is the same used throughout the series of the TX range PSU's and possibly others ranges as it does appear lots of people are having the same problems with some customers resolving there own problems by swapping the PSU for a different brand leaving them to question the Corsair they have purchased.

Ok its late and I am so tired so I am going to wrap this up now but will be keeping more than a close eye on the forum to see other similar stories evolve.

Regards

AndyBoyo

The email was sent but as requested I have now sent it to the 2nd address.

AndyBoyo