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My PC wouldn't post. It's working now after fiddling with it. (TL;DR at bottom)

I would see the light on the DVD drive blink a bit, the fans start to spin up, then it would just shut off, and attempt to start again. The length of time it would be on for was about 0.5 seconds, to maybe 1.5 seconds before it would power down (it would vary between each boot attempt), and attempt to start up again about 2 seconds later. Also, sometimes it doesn't even try to start up, it shows no sign of life whatsoever when the power button is pressed. When it is not responding at all, it's almost in a different state all together from the other problem, because when it's doing the power on cycle, it always responds to the power and reset buttons, and if I give up and come back, or unplug it and more time passes, it may or may not stop responding all together until later.

First, my specs, then I will list more details, and what troubleshooting I've already done to eliminate a lot of guess work.

CPU: i5 3570K (3.4Ghz)
MOBO: BIOSTAR TZ77A LGA 1155
RAM: Kingston HyperX Blu 8GB 1333
GPU: MSI Radeon HD 7850 2GB
PSU:Rosewill Stallion Series RD600 (600 watt)

I have been having this problem for some time, and it only happens when the PC has been turned off for several hours, usually when it's been unplugged or the switch on the back of the PSU has been turned off for a few hours. The way I've been getting around this problem, partly intentionally and partly because it's just how I use my PC, is just having it in a sleep state rather than shutting it down. The PC restarts just fine, and generally I can shut it down and start it back up without problems, it's usually just extended periods of being powered down that causes it (let's say more than an hour, but I'm not sure).

Here is the basic scenario: I need to clean the area around the PC, or I need to move it, so I unplug it and move it somewhere, a few hours later I plug it in, and it won't start. When this happens I usually open her up and reset the CMOS, make sure the PSU connections are solid, and try to start it again. Sometimes that works, but I don't know why.

What troubleshooting I have done:

I removed the sound card and GPU, disconnected all fans (except for the 2 CPU fans on the hyper 212+ HSF), disconnected the HDD and DVD drive, and unplugged the front panel USB connectors. Essentially I stripped it bare, with just CPU and RAM. This did not work, at this point it was completely unresponsive, no reaction to the power button whatsoever. I thought maybe it's a problem with the case's power button, so I tried the power on button on the MOBO, and still nothing. I was at a loss here, so I decided to check to see if it was a shorting problem, and pulled the MOBO out, and plugged it in while it was on it's anti static packaging.

At this point it was just CPU/RAM on the bare board, with the PSU cables plugged into the 24 pin and CPU power. Once set up, I attempted to turn it on, and still nothing. I gave up, came back like 20 minutes later and fiddled with it, and it began responding, the reset button was fully responsive and cause the board to reset (the MOBO has a 2 digit LED to confirm), and would power off immediately with the power button. It would however take several presses of the power button to get it to start, or I would have to wait like 5 seconds to press it after powering down for it to work the first time (maybe there is just a timer that prevents instant power down/up).

I then rebuilt it and after some fiddling it would boot to the OS. I went to sleep, woke up and it wouldn't turn on today, and did the power up/down cycle, then stopped responding, then later it finally turned on.

Sorry for the long post, I tried to be as detailed as possible. Any help or suggestions (I am willing to do further troubleshooting) would be greatly appreciated.

TL;DR:

PC won't turn on (it's working now, but after being turned off or unplugged for a while the problem comes back), is sometimes not responsive to power button, and sometimes just tries to turn on but fails to post and keeps restarting. The problem is either: RAM, motherboard, or power supply. Please help.

I would try a different PSU first. Preferably different brand and/or model. Really sounds like the PSU is either bad, or doesn't get along with your mobo (I've had that happen a couple of times before, where an otherwise good mobo and PSU just wouldn't play nice with each other).

I've had this PSU/mobo combo for almost a year now, and it hasn't always had this problem, only the last few months. However I will try swapping this PSU with another 600 watt (different brand) I have in my other PC, and observe both to see if there are any issues.

For some reason (cost-cutting, probably...) PSUs are one of the least reliable components in a modern PC. IMO they're up there with HDDs and optical drives in terms of failure rates.

Not saying your PSU is *definitely* the problem, but it is the prime suspect at this point.

It still blows my mind that the Biostar I knew in the 90's survived to this day. They're definitely not the same company, it seems like a decently constructed board.

Your PSU on the other hand... going just by the Newegg reviews, infant mortality on it is very high.

A small point but don't rest the mobo on the anti-static packaging and try and start it up. The bags are conductive and may introduce a weird fault and throw you off the scent.

I am definitely guilty of "cost cutting" on the PSU, but at least this one isn't one of those bargain "found it in the trash" PSUs. I used one of those before, and aside from being low wattage, it was surprisingly reliable. I ran it for a few years, and luckily retired it due to the wattage, rather than it going and taking everything else with it

It's really hard for me to justify buying a more expensive and lower wattage PSU for reliability's sake, since in my personal experience I've never had a PSU problem before (I tend to swap them out and cycle them down through my other systems, until I retire them), and I don't have a personal gauge for how cheap is too cheap. If the problem indeed is the PSU, this may be the lesson I need to finally stop buying the cheap power supplies.

The next time the problem comes up I'll do the swap and I will report back here to satisfy curiosity.

And yes, while I won't recommend my motherboard to anyone (I recognize Biostar as a budget/low end brand), I am really happy with it. It was one of the cheapest I could find, and yet has really nice features for the price, and is solidly built. At the time of purchase it was about $70, and has a little display that shows error codes during POST, and shows CPU temp after it boots, plus the little power/reset buttons are incredibly handy for troubleshooting. I'd say it's a quality board and is decent enough for a bit of modest overclocking, it has been for me anyway. (that was all said assuming that it's not the cause of my current power on problem, if it is, I take it all back )

DieselPig wrote:

A small point but don't rest the mobo on the anti-static packaging and try and start it up. The bags are conductive and may introduce a weird fault and throw you off the scent.

Thanks I'll remember that, I did have it on the foam, with the bag below that, which is probably why it worked.

MEATLOAF2 wrote:

DieselPig wrote:

A small point but don't rest the mobo on the anti-static packaging and try and start it up. The bags are conductive and may introduce a weird fault and throw you off the scent.

Thanks I'll remember that, I did have it on the foam, with the bag below that, which is probably why it worked.

The bags and foam are conductive, but have pretty high resistance so it isn't anywhere close to being a dead short. Setting the board on the bag and/or foam while powered up generally won't cause a problem.

Put in a new CMOS battery.

Flash the BIOS to the latest version. It's not the most obvious solution (the PSU is) but it won't do any harm and sometimes when you get unreliable booting it's because the BIOS keeps trying to POST by cycling through various safe modes, some of which don't work.

I replaced the PSU with a corsair 750 watt, and replaced the 7850 with an R9 290 (I really wanted to go NVIDIA this time, but $250 was too good to pass up). Well, I literally replaced everything except for the CPU/MOBO, and built a new machine with the old parts, and some stuff I had lying around. Not because of the power problem, that'd be the equivalent of trying to nuke a fly, just figured it was time to upgrade.

Both systems work just fine, so it must have been some kind of incompatibility. I replaced so many parts at once that I can't pinpoint the problem, but before that, I did try reseating some parts, flashing the MOBO bios, and resetting the CMOS (although I didn't replace it), and the problem never went away. It was most likely the PSU not playing well with the rest of the hardware setup.

I did at one point find an odd trick to get it to start: when the system was repeatedly trying to boot, if I timed it correctly, and pressed the reset button just as the power led lit up, the system would start right up.

On a side note, as someone who builds and maintains their own rigs, I invested in a PSU testing device long ago.

I cant tell you how valuable that tool has turned out to be, like just brew it said, PSU's tend to be one the least reliable components around.

hope i don't jinx myself

got a COOLMAX V-600 PSU and it's running great since Sept 2009

knocks on wood

SoM wrote:

hope i don't jinx myself

got a COOLMAX V-600 PSU and it's running great since Sept 2009

knocks on wood

The jinx would be from choosing a dodgy power supply, if it's anything like the Coolmax V-500.

http://www.hardwaresecrets.com/article/ ... eview/1366

Chances are good that the V-600 won't deliver anywhere near 600 watts, but that your system doesn't demand anywhere close. If it's like the V-500, it uses cheap, Chinese capacitors, has very poor efficiency, problematic voltage regulation, and noise/ripple issues, and it probably doesn't have over-current protection. I'd have very little reason to trust one.

To Quote Meatloaf2:

It's really hard for me to justify buying a more expensive and lower wattage PSU for reliability's sake, since in my personal experience I've never had a PSU problem before (I tend to swap them out and cycle them down through my other systems, until I retire them), and I don't have a personal gauge for how cheap is too cheap. If the problem indeed is the PSU, this may be the lesson I need to finally stop buying the cheap power supplies.

The important thing to remember is that more expensive lower wattage power supplies actually deliver the power they claim to. Cheap power supplies rarely deliver the power they claim to be rated for. Raidmax, Coolmax, and a bunch of other inexpensive vendors are famous for making claims that they'll never be forced to match. Whereas, a SeaSonic SSR-450RM may be $80 for a 450w power supply, but will not only adhere to the 80Plus Gold efficiency standards it claims, but will deliver a true 450w, and probably a bit more if stressed. It will also deliver the voltage regulation the average person generally just assume a power supply does (plenty of the cheap units are way off) and be within spec for voltage ripple.

Hardware Secrets has some great explanations of power supplies for those that are interested; it's worth the read.

Anatomy of Switching Power Supplies
http://www.hardwaresecrets.com/article/ ... pplies/327

Everything You Need To Know about Power Supply Protections
http://www.hardwaresecrets.com/article/ ... ions/905/1

If reading about power supplies isn't your cup of tea, then at least use sites like Hardware Secrets, JonnyGURU, and HardOCP to do your work for you in finding a power supply you'd be interested in using. That way you avoid a crap product. PSUs may not be sexy, choosing the right one probably won't give you another 5-10FPS in your favorite game. But it will greatly reduce the chance of damaging the other equipment you saved your precious cash for, keep your system cooler and possibly quieter, and ensure you don't have odd issues you just can't explain or easily troubleshoot during the course of using your PC.