Member Avatar for elonepb

Custom built PC been working great for 3 years, then it stopped booting up. Well, that's not entirely true, but I'll explain further.

Basically you push the power button, fans come on whirling but the HD light never lights up, and nothing comes on the screen. I get no beeps from bios, and no indication that there is something wrong. Of course it used to be if I left it off for about 30 min after trying to boot it up, sometimes it would actually turn on and work fine.

However it's been 2 weeks since that last worked (should've just left it on grrr), and now it's pretty dead. I did the usual, pulled out the RAM, gfx card, bios battery - turned the PC on and no bios or beeps, just fans whirling.

Thought I must have either a dead motherboard or a dead CPU since it's not even getting to the bios. Bought a new bios battery, no dice. Bought a new motherboard and tried with all my old parts + new mobo... no dice. Went ahead and bought a new CPU, put it in last night, no dice.

Unless they shipped me a bad CPU, what could the problem be? Power supply?

Any help would be GREATLY appreciated!

For reference purposes here are my main components:

Maxtor DiamondMax 10 6V300F0 300GB Serial ATA7200RPM Hard Drive w/16MB Buffer
CoolerMaster TAC-T01-E1 Wave Master
Asus P5N32-SLI Deluxe
Antec TruePower 2.0 EPS12V 550W Power Supply
BFG GeForce 7900 GT PCI Express 256MB DDR3
Intel PentiumD 940 3.2GHz
Kingston HyperX KHX6000D2K2/2G 2GB Kit DDR2-750 PC2-6000

  • 8 Contributors
  • 14 Replies
  • 242 Views
  • 7 Months Discussion Span
  • Latest Post Latest Post by PcTestCard.com

Dani AI

Generated

Quick recap: reported fans and board LED but no POST, no beeps and no HDD activity. Several good starting ideas already appeared (PSU swap suggested by , minimal‑hardware checks by , monitor test noted by ), but a few higher‑value diagnostics and failure modes weren’t spelled out and are worth trying before more parts are bought.

Useful checks and a practical isolation order (adds detail beyond earlier posts):

  1. Confirm CPU power and GPU auxiliary power: the 24‑pin alone can spin fans while the 4/8‑pin EPS (near the CPU) or the PCIe 6‑pin to the 7900GT is missing—symptoms match “fans on, no POST.”
  2. Measure PSU rails under attempted boot with a multimeter or PSU tester: expect roughly 12.0V (±5%), 5.0V (±5%) and 3.3V (±5%). Voltage sag or large ripple under load points to a faulty PSU even if fans run.
  3. Rule out case shorts and standoff issues by benching the board on an insulated surface (cardboard) — extra standoffs or a stray screw can kill POST while leaving LEDs/fans powered.
  4. Look for bad capacitors or physical damage on both motherboard and PSU (bulging/leaking caps, burn marks), and inspect the CPU socket for bent pins—these cause silent failures.
  5. Attach a system speaker and/or a POST diagnostic card to capture codes; a lack of beeps could simply mean no speaker is connected, which removes a key clue. Also confirm motherboard BIOS supports the CPU (some boards need a BIOS update to recognize certain LGA775 chips).

Interpretation guidance: stable rail voltages → focus on board/cabling/shorts or CPU/memory; rails sagging or lots of ripple → replace PSU. If benching + POST card still show nothing, the fault is almost certainly power/ground or a dead CPU/mobo pair and professional bench testing or RMA is the next step. This complements earlier suggestions and narrows what to test next.

Recommended Answers

All 14 Replies

Member Avatar for steven woodman

Sounds to me like your spending money before you should. If you removed all the components attached to you board and didnt get any beeps i would definately try plugging in into a new power supply first. or even if you or a friend have an old compatiable suppy around somewhere try that.

Member Avatar for sittas87

ohk lets take a step back you switch your machine on.do you get display?no display?

Member Avatar for elonepb

ohk lets take a step back you switch your machine on.do you get display?no display?

I do not get a display.

Member Avatar for elonepb

Sounds to me like your spending money before you should. If you removed all the components attached to you board and didnt get any beeps i would definately try plugging in into a new power supply first. or even if you or a friend have an old compatiable suppy around somewhere try that.

Really? Even though the fans are spinning and the light on the board is lit green?

Member Avatar for steven woodman

yes that can happen! maybe just not enough power. that exact same thing happened to a computer i was fixing and when i tried another suppy, boom, up she came.

Member Avatar for KrausAnt

I too am having what would seem to be an identical problem so I will attempt to clarify.

During power up all the expected lights and fans turn on, however the monitor does not detect the computer and quickly goes in to power-save mode. My computer had been running for almost 2 years with and has had no substantial software or hardware changes in several months at least. I had turned the computer on for the day and when I returned several hours later it was off if its own accord. I too tried removing/replacing the RAM and the BIOS battery to no avail. Is it possible for a power supply to simply weaken over time and there by cause a computer brown-out?

Member Avatar for sittas87

check this first:
1-does your monitor give orage light
2-turn monitor brightness all the way up
3-if its not onboard GFX switch to onboard to check if its working
if all fails try this
What you can do is remove all hardware except for hard drive (with your OS on it),processor and one stick make sure all your cables is firmly connected especially your monitor signal and power cable.
turn pc on and check for new behaviour
??

Member Avatar for coolraj003

If all is good then the setup that Sittas explained should take you to the bios screen at the minimum which would rule out the Mobo, CPU and RAM being bad.

Raj

Member Avatar for steven woodman

If there are no beeps its not the video. You would get beeps, probably one long beep followed by two short (from my experience).
If there are no beeps but fan come on i would have to say remove everthing including hard drive and leave one stick of ram. then if this dont work try replace that one stick with another. then if nothing try power supply. i repeat, this has happened to me and it was the power suppy just not producing enough to fire up pc but enough for fans.

Member Avatar for KrausAnt

I replaced the power supply with a new 500W just like the old one and it still has the same problem. Any thoughts?

Member Avatar for steven woodman

If you completed all the suggestions posted including taking all components off the main board except one stick of ram and cpu then i would have to say its being caused by your tower ( that is if your doing all this inside your tower). There could be a problem with the power switch or some other wiring. to tell you the truth reading everything so far thats the only thing left i can think of. There is a way to turn on your pc without using the power switch but you would have to be very careful.

To do this remove all switched led's usb connectors etc from your tower to your board and use an insulted screw driver or something similar to jump the two prongs labeled pwr. you just need to touch them for a second and the unit should power up.

Please if you are going to do this be very careful, you could fry your board or even get electrocuted. The switch is only low voltage but you could slip or something. Anyways i hope i helped im going to read over all the post again to see if anything sparks my mind.

Member Avatar for BigJim45

This thread ended with no mention of resolution. I'm having nearly the identical problem with an HP Vectra VL420 except that it arose following my (apparently foolishly) plugging a keyed 6 pin connector into the perfectly matched socket on the MoBo marked "PSU fan". I have tried all the things that the original poster had done and all those that were suggested without any improvement. Any help would be appreciated but as a minimum I'd really like to know what happened with the problem that "elonepb" was having. Did he ever fix it??
Thanks!

Member Avatar for thepastimer

I noticed when you listed your components off you did not mention a cd drive or floppy. Does this mean you don't have one? One of your drives could possibly be causing the problem.

Member Avatar for PcTestCard.com

I wonder it the monitor ever been tested on other working PC.

Sometimes the semi faulty RAM or oxidized RAM slot may cause no beep but no screen output and shut down.

Hope this helps!
Bill

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.