Is it the CPU or the board?

[RobbieRoy]

Hi All

Have completed my build - the desk looks good and the rig fitted nicely inside (will post about it when all is okay).

However, upon initial power on there is a small 'click' like a relay and the CPU fan spins for a second then stops. Then it is silent, no action although the mobo lights stay. I can't try to switch on again until I've switched off the power and allowed the board to dissipate any charge so the lights go out.

So, I'm thinking either CPU (i7 4790K) or board (Z97 Asus Maximus VII Ranger). I have in stages disconnected everything, removed the PCI-E boards, the SATA connections, the RAM etc, but still the same problem at each try. I've also removed the CPU twice to check its seating and it visually looks fine.

So, by process of elimination I think either the CPU is dead or the board is. I don't know for certain, though, and so would appreciate some guidance from more experienced heads.

Thanks

RR

[herulach]

take the board out the case and do it on the motherboard box with bare minimum components. sounds like a shorting standoff or something to me.

[RobbieRoy]

take the board out the case and do it on the motherboard box with bare minimum components. sounds like a shorting standoff or something to me.

Thanks - I've done that, so with just the power connectors in place, no components apart from the CPU and a DVI cable to the board so I can see if anything happens, but it's still doing it.

Any more I can do?

[adidan]

What's the error reading on the motherboard display?

[RobbieRoy]

What's the error reading on the motherboard display?

It doesn't even light that led display, just the red 'Start' button and the red illuminated track showing the audio circuit. So, no error display, just a click and nothing.

[herulach]

last check would be powersupply and (just for giggles) motherboard switch (just short the pins on the board with a screwdriver it doesn't have its own on button.

[RobbieRoy]

Power supply is a brand new Corsair CS750M hybrid modular and without the ATX power connector attached the board doesn't even light up. The problem is the same whether or not the CPU power is attached.

As for the switch - this board has a big red illuminated one with 'Start' printed on it - and pressing that gives the same result as shorting the power up pins with my screwdriver

[woodi]

Have you tried the paperclip method to make sure its not the power supply?

[bean0]

Sounds like the motherboard to me, if it was the CPU I would expect it to power up but not do anything

[RobbieRoy]

Okay - many thanks for the extra replies.

I think I've narrowed it down to the PSU (top marks herulach!).

Having completely removed the board and used an old Dell 180W PSU salvaged from a dead rig I got it to work and boot to the BIOS when sitting on the kitchen table.

I then removed the new PSU from its frame and used it and, again, all was fine. So, I returned mobo and PSU to the case and started to reconnect all, checking at each stage.

All was well until I started to plug in more than two type 3 connectors into the back of the PSU, whereupon the issue arises again. When 'stalled', if I pull one of the type 3 connectors out the PSU spontaneously starts up correctly and the machine boots up. There is some variability in that it will sometimes stall with two connectors in or not with three.

So, PSU seems wonky and so I will be contacting Scan to RMA it.

Thanks again everyone and hopefully the thread will be useful in the future for someone with a similar issue.