A recent FS computer upgrade left me with an old computer to rebuild and purpose for our home "office" that has not had a computer ever before.  The computer build itself has been on the shelf for about 5-6 weeks, but worked perfectly fine when it was last powered down.  A couple hard drives were reused on the FS computer and the graphics card swapped back to an older graphics card.  No core components were changed.  The build was moved from a gaming style case that wasn't felt to be reasonable in appearance for a more public space in the home to a different, more contemporary case.  

I currently have everything seemingly connected, but nothing will happen with the power switch.  No fans, no error codes, no POST, nothing.  The core of the system is: Asus Z97-Pro, i7-4770k, GTX 970, 750 W Corsair PS.  From what I have tried, troubleshooted, and tested so far:

1. I don't think the power supply is the issue.  There is a power switch directly on the motherboard with an LED light that lights up.  This is lit up.  The switch does nothing, but the LED works.  Of course, this doesn't mean every phase of the PSU, the CPU power bundles, PCI and SATA works, etc.  But there's something coming from the PSU.  Other than completely disassembling my new FS rig (extensively zip tied and cable managed, no small task), I have no other power supply to test.

2. The CPU was not removed while moving the MB.  The Noctua air cooler was removed (it blocked MB riser screws) and reseated (with new thermal paste of course).  The CPU worked before, so while this is no guarantee, I am skeptical anything really changed with the CPU

3. RAM likewise was not removed

4. The front panel switches have been double checked several times.  Additionally, the power switch directly on the MB does nothing.

5. I do not have a system speaker to test for beep codes, but there is a LCD display on the MB that is also supposed to report error codes, and nothing displays.

Does anyone have any additional thoughts on troubleshooting?  I suspect this has to be MB, PSU, or CPU.  Anything else should boot enough to get some error code or other information.  But with only a single unit of each, all used in the build, I don't have any further ideas how to test this further.  I would like to minimize cost in this current system.  We're only in it for about $80 so far that was used on the new case.  If all that was needed was an inexpensive MB or PSU, I would consider replacing those parts.  However, since this will be an office computer, we wouldn't spend much money on this before moving on to a cheap off the shelf Best Buy or similar PC that would serve the office role just fine.  This is primarily based on the financial aspect, since these can be had for as low as $3-400. 

Edited January 17, 20197 yr by ESzczesniak

Sounds like dead PSU.

You probably already know how, but Test the PSU like this video. If the fan spins, you're probably OK with the PSU.

Otherwise, reseat the power connections.

Another thing I have tried in the past, unscrew it from the case, and try it on something none conductive (I usually use the box off the motherboard).  It could be a screw in the case shorting it.  I've had this a few times in  the past

Thank you both.  I did not know about the trick to test the PSU.  The fans do spin up.  Removed from the case and isolated, but connected to the MB does not resolve the issue though.  It seems at this point either CPU or MB, but I'm suspecting MB presently.  I'll mess with this a bit more, but I'm suspecting this may be left for what it is, as the CPU will still be more than I want to spend, and I think a new MB would have to be a second hand market, which isn't the most appealing to me. 

That PSU test in the video doesn't tell you much except that the PSU is not completely fried.  A decent PSU tester only costs $20-30 at someplace like Newegg, and will give you a go/no-go on each of the circuits.

Since you removed the CPU cooler, make sure that the notch on the CPU heatsink backplate is correctly oriented and the backplate is not contacting screws/electronics on the back side of the board.

My gut suspicion is that the PSU's ground fault detection is preventing the PSU from powering up.

Regards

 

I had a similar situation with my new PC I just built Monday.  It was an ASUS z390 with a 9900K.  I came from an ASUS Z170 with a 7700k and in swapping the MB I plugged the CPU 8 pin  power in backwards which meant no post, boot or anything.  The RGB would light up on the board and the lights on the GPU would light.  ASUS had reversed the CPU power connectors and I was not paying attention to what I was doing.  Corrected the 8 pin power and it booted right up. 

Just something to check.

Do you have power to cpu from mb connected?

So many things it could be.

Most obvious is PSU. If in the UK, I'd say to first check the fuse in the plug, but in the USA I don't believe you have fuses in your plugs.

PSU's have a switch on the back of the unit. So easy to not notice it's been flipped off. Although you say you have an LED alive on the board, so not applicable.

Something you wont probably be aware of, but often works, is to discharge the capacitors. To do so switch the PSU completely off at the wall. Hold your finger on the case start button for 30 seconds or so. Then switch on and try to boot. This will often send the "power good" signal and the PC boots.

Personally I have an Antec PSU tester that checks the voltage on all rails. Cheap on Amazon. Don't be fooled into thinking that just because a PSU fan is spinning that the unit is sound. A PSU tester wont tell you how it functions under load, but that's not a concern for you at this stage. 

Possible that you have a short somewhere, and the PSU's OCP is shutting off the unit. Although I would be surprised if an LED was still alive on the board, as OCP usually shuts off all power. 

You've probably already done so, but check that the 24 pin and CPU 8 pin is connected properly, in fact remove, check pins and reinsert.

As Is aid, a PSU tester is dirt cheap and has proven to be a very useful tool for me over the years. Get a speaker too, they are really cheap and the POST codes are invaluable for trouble shooting. 

https://www.amazon.co.uk/DIGIFLEX-Power-Supply-Tester-Diagnose-Black/dp/B004IO5CT8/ref=sr_1_1_sspa?ie=UTF8&qid=1547906597&sr=8-1-spons&keywords=PSU+tester&psc=1

 

If you get a PSU tester (or use a multi-meter) pay attention to the +5 Volts. The PSU needs this signal to boot. Also remember that a defective graphics card can prevent a PC from booting.

 

 

Edited January 19, 20197 yr by martin-w

On 1/18/2019 at 12:08 PM, mulgrave said:

Do you have power to cpu from mb connected?

 

Yep, if the CPU 8 pin isn't connected it won't boot. Worth checking also the pins to ensure they are sound.