[SOLVED] New PSU, now system will not boot, POST, or fans run longer than 1/2 second

[dash14251]

This is an Asus I bought about 8 years ago, CM6870. It had been in sleep/hibernate for a few weeks and yesterday I went to wake it up and it was off.. weird. I found the PSU that I had replaced about 5 years ago was bad (paperclip test) so I grabbed a new one, same watts, etc and put it in.

When I hit the power button all the fans start up for just a split second and then turn off. They do this every 3-5 seconds and nothing boots up or runs continuously. I'm getting a solid green light on the motherboard with no beeps or flashes to indicate the issue.

I've read through numerous similar issues on this forum and double checked connections, tried switching out ram sticks to different locations, even replaced the CMOS battery.

Currently, I have the motherboard removed from the case to eliminate possible shorts on the back of the mobo. Everything has been removed and disconnected from the mobo except the 24-pin power connector and the CPU 4+4 connector, and the power button connector and it's doing the same thing. The PSU fan starts for split second and stops, then it does this over and over every 4 seconds or so.

At this point, with everything removed (all RAM, GPU, fans, everything except power cords) I'm thinking it has to be either the CPU (Core i7 3770) or the board, correct? I would think that even in this stripped down state that I would at least get some kind of action past the green light and the PSA fan turning on and off constantly. It does this exact thing even with the CPU connector removed.

I removed the CPU just to see what happened and I still got the green light on the mobo but the PSU fan wouldn't even start that time.

Any suggestions would be appreciated!

 

[Aeacus]

I found the PSU that I had replaced about 5 years ago was bad (paperclip test) so I grabbed a new one, same watts, etc and put it in.

1. Paperclip test is obsolete, since it doesn't tell if PSU actually works. What it does, is just turning it on, without putting any load on it. And many modern PSUs have semi-passive fan in them, where the fan doesn't turn at all at low to medium loads.

PSU paperclip test is like when you turn on the car engine and instantly assume the car drives fine, without ever driving the car.

2. PSU make and model (or part number) is? Both what you had earlier and the "new replacement".

Everything has been removed and disconnected from the mobo except the 24-pin power connector and the CPU 4+4 connector, and the power button connector and it's doing the same thing.

3. PC won't work without RAM and CPU cooler. So, when breadboarding, always keep CPU, CPU cooler and RAM, since these are bare minimum to POST and get into BIOS.

4. What it looks like, is a dead MoBo.

 

[dash14251]

1. Paperclip test is obsolete, since it doesn't tell if PSU actually works. What it does, is just turning it on, without putting any load on it. And many modern PSUs have semi-passive fan in them, where the fan doesn't turn at all at low to medium loads.

PSU paperclip test is like when you turn on the car engine and instantly assume the car drives fine, without ever driving the car.

2. PSU make and model (or part number) is? Both what you had earlier and the "new replacement".


3. PC won't work without RAM and CPU cooler. So, when breadboarding, always keep CPU, CPU cooler and RAM, since these are bare minimum to POST and get into BIOS.

4. What it looks like, is a dead MoBo.

awesome thanks for the help!

1. that's fair just now I checked it with a multimeter and not getting any readings from the 24 pin dongle on the old one. checked the new one and I'm getting proper voltage for all color wires, except blue is only -11.38 and I think should be -12. would that affect startup?

2. old psu is a 500w epower model EP-500PM and the new one is the Thermaltake Smart 500w, p/n PS-SPD-0500NPCWUS-W

3. I know it won't "work" without those but figured it would at least get past the fan motor starting for a half second. I was just trying to rule out as much as possible and put the least load on the system but yeah I can leave the CPU fan plugged in and a stick of RAM. I was hesitant because maybe one of the 4 sticks was bad and causing it.. should I just start with 1 in the #1 slot?

thanks again for reading this. I'd love to resurrect this old girl, clear it and reinstall windows, etc if possible. hate to throw good parts away if I can help it

 

[Aeacus]

old psu is a 500w epower model EP-500PM

Essentially a no-name PSU, with highly questionable reliability. Most likely a reason why your MoBo was fried, since when PSU acts up, MoBo is usually 1st one to go. 2nd one to go, usually, would be GPU. CPUs are very durable and can survive most, but they aren't invincible either.

Thermaltake Smart 500w, p/n PS-SPD-0500NPCWUS-W

Low quality PSU. Only small step better from the crap quality Epower you had before. Still, even Tt PSU isn't nowhere enough of a build quality and reliability, for it to be used in any system.

For good quality PSU, look towards Seasonic Focus+ or PRIME series.
(All 3 of my PCs are also powered by Seasonic, full specs with pics in my sig.)
Or when you prefer Corsair, then RMi, RMx, HX, HXi, AX or AXi series.

You can cheap out on every component inside the PC, except PSU. Since PSU powers everything, it is the most important component inside the PC. And low quality PSUs have the magical ability to fry everything they are connected to, when they go sky high. Things can go as bad as PSU catching fire and burning down your entire home.

In a similar example, and with cars; would you buy the cheapest tires you can find, for your car? While keeping in mind that tires are the only things touching the ground.

except blue is only -11.38 and I think should be -12. would that affect startup?

According to ATX PSU standard, +/- 10% on -12V rail is within spec.

PSU Tolerance Table
Voltage Rail	Tolerance	Minimum Voltage	Maximum Voltage
+3.3VDC	± 5%	+3.135 VDC	+3.465 VDC
+5VDC	± 5%	+4.750 VDC	+5.250 VDC
+5VSB	± 5%	+4.750 VDC	+5.250 VDC
-5VDC (if used)	± 10%	-4.500 VDC	-5.500 VDC
+12VDC	± 5%	+11.400 VDC	+12.600 VDC
-12VDC	± 10%	-10.800 VDC	- 13.200 VDC

should I just start with 1 in the #1 slot?

You can try. However, based on your description and the crap quality PSU you had, it is looking very likely that your MoBo is dead.

Though, to test and rule out which of the three: RAM, CPU and MoBo, is dead, you need 2nd, compatible system, where to test those three components individually.