Member Avatar for dlivezey

Dell 4500 was working fine up until yesterday but today, cannot power on.

Tried:
- Removed front cover - switch seems okay mechanically
- Removed RAM, all drive connectors, and all cards except graphics adapter. Still nothing - no beeps, no signal to monitor

Other observations:
- No fans running now
- Small green light on mobo is on
- No other lights or activity
- Was pretty dusty, some paths pretty clogged
- Main CPU cooling fan turns easily by finger, not jammed

From reading other posts, it sounds like the most likely culprits are:
- Motherboard / CPU
- PSU

I lack knowledge, tools, and replacement parts/machines to troubleshoot any further. Any best guesses as to the probable cause? If it seems 70-80% likely to be the PSU, I may just roll the dice and buy another.

Thanks for your help!

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  • Latest Post Latest Post by christian24

Dani AI

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Short, practical troubleshooting for (and others like ). Cleaning is a good first step (thanks to for that reminder), but when a machine shows only the board “standby” lamp and otherwise gives no fans, beeps, or POST activity you want to separate a bad PSU from a motherboard fault with a small, safe set of tests.

Start with a minimal, safe bench procedure: unplug the PSU from the motherboard and all drives, place the board on cardboard, connect only CPU + cooler (fan plugged into CPU_FAN), one stick of RAM, and the GPU if there’s no onboard video. Try powering it. If nothing happens, try the PSU standalone test: with the PSU disconnected from the board, short the PS_ON (green) pin to any ground (black) on the 20/24‑pin connector to see if the unit runs. Do this only if comfortable and unplugged until the moment of the test; do not touch exposed metal while it’s powered.

If the PSU starts, measure the main rails with a multimeter: 3.3V ≈ 3.3V, 5V ≈ 5V, 12V ≈ 12V (rough tolerance ±5%). The 5VSB (standby) should be present even when “off.” If the PSU fails the paperclip or voltage checks, replace or borrow a known-good PSU and retest. If the PSU appears healthy but the system still won’t run, the motherboard (or rarely CPU/VRM) is likely at fault.

Also visually inspect the board and PSU for bulging or leaking electrolytic capacitors, burn marks, or a nasty smell — these are strong indicators of failure. Try shorting the front-panel power pins briefly with a screwdriver to rule out a faulty case switch, and clear CMOS by removing the battery for a minute. If you’re unsure or lack tools, swapping in a borrowed PSU or taking the machine to a local repair shop for a bench diagnosis is the fastest, least-risk option.

Member Avatar for eliolum

hi,
think the best way is to start by blasting the whole machine and use a blower to clean the machine then put back the peripherals back i.e drives and other cards one by one as you are trying to power on......if that fails as u are saying there is a green light yuo are seeing that gives the psu the benefit of doubt in that the power actually gets into the pc.........have had the same problem with my dell and solved it by the above method..........
best regards

Member Avatar for christian24

hi i have the same problem but i blow out the whole motherboard and put back all the peripherals one by on and still nothing what should i do?

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