New PSU-Won't boot

[johnwillyums]

Hi folks,

A couple of weeks ago my PSU failed. I was just reading an email and suddenly the pc just stopped. I thought I'd turned the power off with my foot, no smell, no noise, it just stopped.
I RMAd the PSU and it has been replaced by a Corsair AX850 and I spent hours yesterday installing it and trying to get it working but failed.
I have a Gigabyte EX58-UD5 mobo and 6GB of Corsair XMS3 RAM.
The PSU is fully modular and I've been trying various ways of connecting it but when I press the on switch nothing happens.
Just once it started up but I did not have the monitor connected so I shut it down and it hasn't done so since.
I have a couple of LEDs lit on the mobo but when I push the start button it does not even attempt to start. No fans start, no more lights appear on the mobo. Zero.
I wonder if it's the tiny power switch and reset etc pins but can't see why it should be them that's failed. Also there is a blue lit square button on the mobo that I believe should start the boot but it doesn't.
I'm at a loss as to what to try to sort this out. Could it be a faulty RAM stick?
I'd appreciate any suggestions as to how to get this sorted out or any way of diagnosing what is wrong.
I can't think it's the RAM as the failure was so painless and the PSU company say that it had failed completely. Could it have taken a stick of RAM with it?
If so would that cause this total failure to attempt to boot?
I feel I may have something connected wrongly as it shows no sign of life at all other than the mobo lights.

Help would be appreciated, thanks, John

 

[Morph666]

I had a smilair problem with one of my older builds once. I put a new powersupply in (Aero Cool 550W), I switched the powersupply on and one motherboard led came on. I smilingly push the powerbutton on the front of the case and...nothing. After messing around a bunch with the tiny plugs for the powerswitch and led lights (they're still all connected to the FP1 connectors on the motherboard, just in a different order) then it finally came on. Maybe your problem is as simple as mine.

 

[Dwarf]

Hi John,

Double check all motherboard and PSU connections. In particular, many newer PSUs have voltage-sense feedback circuitry to ensure stable output voltages. This function is usually provided by means of a feedback cable that is wired into the motherboard end of the main connector. Check that if you have such a connector that you have plugged it into the PSU.

 

[FliGi7]

There is certainly a possibility a voltage spike from the PSU could have friend something on the motherboard or one of your components. It's hard to say. I would disconnect all hard drives, optical drives, and take out all of the memory. Make sure only the 24pin power from the PSU is hooked to the motherboard and that it's a good connection, then try booting it up to see if it will get to the BIOS screen. If not, either your motherboard is dead or the PSU is.

BTW, that's a really nice PSU.

 

[johnwillyums]

Thanks Morph. I think you might be right. When I first built the pc (14 months ago) I had a similar problem and after much messing about it was finally sorted. However I never managed to get the reset button to work.
I know that I have followed the mobo guide to the positioning of those connectors but I'm sure they are not in the same grouping as they were before.
Also, on one configuration I achieved a blue power led on the top panel. That is no longer appearing.
I think I'll get my camera from the car and post some pics of the them. perhaps someone with the same mobo can put me right.
Thanks for your input

 

[johnnya]

You have probably checked this a dozen times already but have a look.
There are only two (2) plugs from the power supply that connect directly to the Motherboard. The large 24 pin main plug, and then there is a 4 pin plug that also plugs into the Motherboard. Are they (both) connected and securely seated?
Cheers
JohnnyA

 

[FliGi7]

You have probably checked this a dozen times already but have a look.
There are only two (2) plugs from the power supply that connect directly to the Motherboard. The large 24 pin main plug, and then there is a 4 pin plug that also plugs into the Motherboard. Are they (both) connected and securely seated?
Cheers
JohnnyA

This is true. Forgot about that one!

 

[johnwillyums]

Thanks for all your replies folks. I've been rapidly reorganising my table to accomodate two pcs. I've taken some pics of the mobo and in particular the power switch connector, reset and LED pins.
I can't help thinking these are wrong but , as I say, I've followed the guide in the mobo manual.
Basically the hard drive activity LED ( blue&white 2 socket pin) goes in the little box bottom left, the reset switch (purple&white 2 socket pin) directly beside it. On the top row of pins the power LEDs (1 blue& 1 white) and then the power sw (red&black 2 socket) goes next to them on the top row.
The more I look at them the more I think they were not like that before but that is what the manual says. I have a feeling that a couple of them were outside this little box but I can't be sure.
here's the pics:

 

[Hopalong X]

This might be stupid but would a dead CMOS battery cause the problem?

It just died totally or lost contact.

No throwing things at me if I'm way off on the thought!

Mike

 

[johnwillyums]

I don't know Mike. The battery seems to be seated ok and I do have a green and yellow LED on the mobo plus a blue light behind what I take is a start button on the mobo. Would I still have those if the battery was dead?
Here's a pic of the little front panel header pins:

 

[Sardonicus]

Have you tried plugging in the 8 pin PSU connector, instead of the 4 pin connector.

 

[johnwillyums]

Not sure what you mean p5. There's a 10 pin (top right in the pic of the psu) and an 18 pin bottom right. These connect to the 24 pin going into the mobo on the right hand side.
The yellow plug is a 10 pin (only 8 active) going to an 8 pin ATX 12 volt on the top left of the mobo. I don't seem to have a 4 pin connector.
I'll try what flig suggested. Back in a minute as I have t0 reconnect the monitor and switch this pc off. This is getting me down.

 

[Dwarf]

The CR2032 coin cell battery only provides power to maintain the CMOS and RTC (Real Time Clock) when the computer is disconnected from the mains supply. Its presence, or lack of it, has no effect whatsoever on the normal running of the computer, save that if it was missing/dead it would just simply mean that you would need to reset the BIOS settings each time you apply mains power after having said power removed.

 

[Sardonicus]

Not sure what you mean p5. There's a 10 pin (top right in the pic of the psu) and an 18 pin bottom right. These connect to the 24 pin going into the mobo on the right hand side.
The yellow plug is a 10 pin (only 8 active) going to an 8 pin ATX 12 volt on the top left of the mobo. I don't seem to have a 4 pin connector.
I'll try what flig suggested. Back in a minute as I have t0 reconnect the monitor and switch this pc off. This is getting me down.

Take a look at image number 10.
All about the various PC power supply cables and connectors

 

[Anak]

I don't know Mike. The battery seems to be seated ok and I do have a green and yellow LED on the mobo plus a blue light behind what I take is a start button on the mobo. Would I still have those if the battery was dead?
Here's a pic of the little front panel header pins:

John I have noticed whenever I worked on the MB the connections should be marked to match where those header pins would go...Steve

 

[Sardonicus]

You power supply is an
ATX12V v2.31 / EPS12V

I would use the 8 Pin PSU connector that came with your PSU.
The 8 Pin PSU power connector, like the 4 Pin PSU power connector
is what you plug into the motherboard for power.

You know, that 8 slot white power connector on the motherboard that many people only plug the 4 pin connector into.

 

[Anak]

For everyone else here are the connectors John is working with.

Professional Series

 

[Sardonicus]

For everyone else here are the connectors John is working with.
View attachment 145499
Professional Series

Ok, I see.
Great.
Disregard my posts!

 

[johnwillyums]

Anak. Yes I have followed the diagram in the manual, it does specify where the pins go.
Flig, I tried what you suggested, unplugged everything except the 24 pin ATX and the 8 pin 12v ATX. Nothing at all happened, no fans no nothing.
P5. Maybe this is where the problem lies. I don't seem to hjave an appropriate cable for the 12v ATX at the top left of the mobo. I can't find one in the Corsair cable bag that will fit. This is why the 12v ATX is yellow in my pic. It's the old one from my previous PSU.
I'll have another look but I couldn't see one before. Does it matter that some of the pin sockets have a rounded end and some don't. The cables supplied by Corsair do not include one with the same pin profile as the old one I'm using.
I'll take it out and have another look.
Remember this thing actually started, fans, power etc once, but I stopped it because I did't have the monitor connected and it hasn't started again since.

 

[QuackPot]

I had a problem like that. Turns out one of the pins in the 24pin cable was bent and I have to twist it a bit and it solved the problem.