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Did my mobo die while sitting unplugged? (was "Please help me check my power supply")


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Yes, I did re-seat the CPU - no change.  There's no instant overheat, either.  I haven't ruled out any issues with the case switches, however.  I've emailed back & forth with ASRock's tech support and it's been suggested that the power on, no post issue is the result of the CPU & FSB not syncing up.

Regarding buying new hardware, I'm willing to buy a new mobo to see if that's the issue, but buying an expensive CPU just to test a theory is out of the question.  Although, it occurred to me as I was typing the last sentence, I could try to find a older, used socket AM4 CPU cheap.

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4 hours ago, E-66 said:

no post issue is the result of the CPU & FSB not syncing up.

That is why I have suggested to try my method. CPU can heat up very fast and 25 seconds to shut down due to thermal sounds about right. The air cooling heatsink will not prevent overheating heating due to outputs that are not toggling. The other power supply could be weaker or its output may rise slower. My old Opteron usually sits at 55 degrees but when I had instability after turning on high efficiency ACPI in BIOS I got gobbledygook printed on the screen with a CPU temp of 95 degrees. So I needed to work on the board. I added some caps on the CPU output buss and around the RAM and lowered the high frequency impedance across the main supply caps of  the CPU. I experimented after this with RAM speed on auto which gave the best result on bench so far of over 6000 but after having supply unplugged while working on the other hardware install I had the same trouble as you and I did what I suggested and it booted up OK. I then set RAM speed back to 133 and had no trouble since then with a bench figure of over 4000. Auto setting was 200 MHz and sometimes you need the best RAM or RAM that has more conservative SDP settings or lower speed RAM for a motherboard to boot. I have still trouble on the PCI buss which can be emulating from further upstream and I need to retire my SCSI card which is stopping the software restart/rebooting by not allowing the PCI to fully function. If the motherboard has power supplied to it the network socket should have the green LED lit. This LED light did not go out on my board within the unplugging period I estimate as I investigated it again but not sure about this as I did not look/notice when I did the power cycle after the non-boot episode. The network cable needs to be connected to an active network, a powered up switch should do and the PSU needs the mains plugged in for standby supply. I will be working on the board again shortly but it did lock up sudden just tonight and after about 15 seconds it shut itself down. It did not happen after this as the transistors and capacitors heated up I estimate but still had a stutter every so often for a while. It is unacceptable and I value the hardware so necessary attempted repairs will be taken.

Edited by Goodmaneuver
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If I let it power cycle for the 25-30 secs that it has been and the CPU heats up as much as you say it could, then shouldn't I be able to feel that in the heatsink?  I've never checked that before but I'll fire it up again and see what happens.

I hadn't made any changes to the stock BIOS settings when the PC was working previously, and just left them at stock and auto.  That being said, I did spend a fair amount of time in the BIOS just looking around, and I don't remember ever seeing CPU temps of 40 or higher.  I just rebooted the PC I'm using now and checked the CPU temp.  37, and its heatsink & fan are much smaller.  I do have the BIOS set to control the fan speed as needed, and it rarely spins fast enough for me to even hear it, and I have the side of the case off.  That's a different PC, of course.  I'll see if I can feel the heatsink getting hot on the non-booting system and report back.

Edit: I let it go through two of the 25-30 sec power cycles, and I couldn't feel the temperature of the CPU heatsink change at all.  Then I felt the CPU heatsink of my working PC and it *might* have felt slightly warmer.  The only thing that actually had a warm feeling to it was the chipset heatsink.  It wasn't hot though, and I could have easily kept my fingers in contact with it all day.

Edited by E-66
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7 hours ago, E-66 said:

If I let it power cycle for the 25-30 secs that it has been and the CPU heats up as much as you say it could, then shouldn't I be able to feel that in the heatsink?

Yes probably but mine has 6 heat pipes and the top of the heat stack is cool and the surface of the CPU can be hot. The heat exchanger/grid section is 9cm cubed. I my heatsink is not big enough theoretically and I have two high speed fans. A heat gun is good to check temperatures, I have a cheap one which works good. When all is OK the CPU will throttle back on yours and it is when CPU load is flat-out is when you need to check temperature. Never the less 40 degrees is indicating that the heatsink is in full contact with the CPU and things are OK. When there is a motherboard fault CMOS transistors are not toggling having a short circuit like condition and the CPU not only heats up due to CPU activity it can have shorted transistor conditions as well. What can happen in booting if the fan speed is set up to operate auto is that it goes fast for a short while then slows done when the hardware is booted and the video output occurs. The fan is set up in auto for CPU temperature changes. I have many boards that do not boot and were second hand. It is best to take note/mark or put aside the best RAM and video cards for testing. The best AMD video card I found is one that stepped down in transistor size and still is the old modal like HD4770 but some boards I got going only booted with a good nVidia. Secondhand CPUs are not advisable unless you are lucky and the supplier tests in several boards. They need testing with a 64bit OS. All of my second hand socket 754 ones I bought from general public individuals were faulty in one way or another, some worked on 32bit OS but not on 64. The best one was one that worked fully but only with 256MB of ram installed. Second hand ones from shops can be weakened and just work on a healthy board. A new CPU should have enough push in reserve to be able to overclock when all hardware is good and used to be about 30% but things may have changed. If you can afford a different CPU then I would try it because the motherboard is new and most sellers should test to boot screen at least. Was the battery still OK it should be over 3 volts otherwise I do not use them. The battery can discharge within a month or two without standby power but depends on the motherboard. This slow decay can be dangerous with different ambient temperature changes and BIOS could be corrupted. I do not store boards with battery in place. Unplug the PSU mains cord, wait for capacitors to discharge, remove battery and short the reset pins for at least 10 seconds to clear CMOS. Make sure shorting jumper is back in the non clearing position. If the shutting down time was closer to 10 seconds then the power switch could be sticking in. I have had that before and some light oil spray on the plastic case button fixed it.

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>>but it just power cycles every 25-30 sec

By this does do you mean that it shuts down then power up itself automatically itself or does it just shut down? If it auto restarts the BIOS can be trying defaults then rebooting. If no beep code then I would try different CPU and is the Corsair CX500M new?

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7 minutes ago, Goodmaneuver said:

>>but it just power cycles every 25-30 sec

By this does do you mean that it shuts down then powers up itself automatically itself or does it just shut down? If it auto restarts the BIOS can be trying defaults then rebooting. If no beep code occurs without video or without RAM then I would try different CPU first and is the EVGA SuperNOVA 650 new as this still could be a problem?

 

Edited by Goodmaneuver
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Why did prior posting happen when I just edited previous post. With modern OSs if the CPU is flat-out the PS2 ports can play up creating all types of different keying errors/functioning but none were visible when I edited. EDIT it is Chrome browser doing this previous stuck through sentence not Microsoft. High light a few lines of text then hold shift key then type as you would a new sentence. It is not the new UI either it was happening prior. Using FireFox now.

Edited by Goodmaneuver
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It powers on, shuts down, and restarts itself.  I let it go through 2 of these cycles while touching the CPU heatsink as close to the CPU as I could, and the only temperature change I could feel was the warmth of my fingers touching it for so long.

None of the components are "new" anymore, as the build is well over a year old, but I bought all the parts at the same time.  I moved the EVGA PSU to my working system and it powers it fine.  I moved the SSD over to my working system and used... I forgot the exact name of the program, but it gives you extended info about your HDD, and it reported that the SSD has been powered on for just over 120 hours, so you can see how little use all of the components have.

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Some motherboards have a lot of capacitance to charge up around the CPU and if the PSU cannot handle this amount on startup it will shut down and only way to reset it is to unplug the mains plug I think. I bought the cheapest 1000W power supply just recently. It was very light weight and has not got enough line filtering and not enough holdup capacitance on the line. Line is the mains side and watching TV is impossible at the moment with the WinME machine running because of the RF emitted into the mains. Line filtering hardware can be added close the the PSU later and it will be essential. My power supplies were burning out with using 3 SCSI drives and all the board components. Admittingly they were probably burnt half out prior to their use. They were cheap 500W ones as an average wattage. The new 1000W one I painted the internal heatsinks black. A good check on whether the PSU is under stress is feel the air temperature coming out of it. If it is warm then there are components getting too hot as there is not enough heatsinking employed and not enough air flow. The new one is fairly cool and that is good. So I recommend trying a larger wattage PSU first on second thoughts as they are not built to last unless lightly loaded and it might be the cheapest alternative.

BTW the added capacitance capacitance I mentioned before was a mistake and it was that that made the startup boot problem I believe. My board has a lot of through hole capacitor positions that were vacant. I removed one that I had installed and no boot problem with BIOS defaults. Voltage startup timing around the board components would be the issue here I think.

Edited by Goodmaneuver
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I don't remember the specifics of the EVGA PSU, but it's a quality unit.  It's 650 watts, which is far more than any PSU I've ever had.  From what you've written, you sound like a power user to me.  I have a SSD and a basic video card, and I don't game.  My PC is a glorified jukebox with a built-in web browser.  I've exhausted my ability to troubleshoot.  For $35 I'll let a tech at a local shop tell me what's going on.

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3 hours ago, E-66 said:

I don't remember the specifics of the EVGA PSU, but it's a quality unit.  It's 650 watts, which is far more than any PSU I've ever had.  From what you've written, you sound like a power user to me.  I have a SSD and a basic video card, and I don't game.  My PC is a glorified jukebox with a built-in web browser.  I've exhausted my ability to troubleshoot.  For $35 I'll let a tech at a local shop tell me what's going on.

And if you add another twenty , you can buy a new motherboard , as it seems highly unlikely that the CPU is damaged .

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The PSU wattage is the maximum rated power and is an intermittent power rating. What we need is the continuous power rating from the manufactures and if water cooling is required so that the components fit in the PSU standard size case and also to satisfy peoples noise tolerance then this is what I recommend. One PSU model did have water cooling that I know of and it was 600W from memory of such. If the Corsair CX500M does not need resetting when it tries to boot the ASRock AB350M Pro4 then the pin 15 or green cable is loosing its grounding. This means that a certain criteria was not met like the voltage did not rise fast enough. To give the 1000W power supply some justice I have 2 extra SATA drives installed along with the 3 SCSI drives in the interim of changing to SATA. My board has 7 3300uF capacitors on the CPU and 3 large ones (cannot be more specific as board is in its case and I did not memorize this) on the 12V side of the inverters. I can count to 10 which would be about 10 seconds before the light on the network socket goes out after unplugging the PSU. You do not need a license to work on computers but you do for low voltage work theoretically this includes repairing a PSU or valve radio. The EMF can be reduced significantly if I use the shortest PSU mains lead. What I have done is have my leads Velcroed together and I had the PSU plugged in on one of the longer cables by coincidence. The Velcroing of the power leads creates a captive shield and to be fair many of these PSUs must have not enough line filtering. My other 550W power supply did interfere with the TV when I had it on the longer lead but not as bad. I just made this discovery and so I updated this post and in conclusion the cheap 1000W PSU is not that bad.

Edited by Goodmaneuver
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