Which part is broken

[sorryboi]

I have an old computer and I am building a new mini build and trying to save as much money as possible so I am trying to reuse old parts I dont use anymore. The computer doesn't boot. When I try to, the fans spin for under a second and then shut off. Whenever the PC has any power at all, a red light will flash on the motherboard.
How can I identify which parts caused it to act this way?

 

[rgd1101]

Start by giving us the full system spec, include make and model of the psu

 

[panathas]

Give us more info about your specs. Also that red light on your motherboard should have a label somewhere. On top of that it's important to note its position. Usually motherboard makers put those led lights close to the components, they represent. For example a GPU failure light should be close to the 1st PCIe 16x slot and so on.

 

[sorryboi]

Sorry about that.
Dell Inspiron 620.
Under the red light it reads "LED 1"
This might not even relate to the light but just incase, under the "LED 1" text says "R756" and above the light it reads "R 699"
( ͡° ͜ʖ ͡°)

 

[Simon Anderson]

As folks above say... need more info. But had a random thought: i know i used to have a Dell, and when you turn it on with the, er "hard" switch (the [I-O] one on the back) the fans would spin, then it would shut off... The red light just shows it's getting power. Did you actually wire up the soft switch? i.e. the switch on the front panel? And did you wire this correctly?

Just thinking, before you start to try diagnose whether it's CPU, Memory, or heaven forbid a Mobo problem, then start with that. From my experience, if it's one of those problems (CPU/MEM/MOBO), the fans will still spin when you turn it on (turn on as in use the soft switch) but you'll get three or four BEEPS telling you something's broken... I believe with Dells the front lights will also display in a certain pattern to give you more info on which bit it has a problem with.

So yeah if yer not getting beeps, or weird lights, and if the fans switching off immediately, i'd check your switch first

 

[sorryboi]

What kind of other info do you need? It is all the normal specs of the 620
The power on switch on the front panel is wired all to one part onto the MOBO.
It's sorta like all of these connectors but in one. I swear you cannot mix their connections up.

 

[sorryboi]

Power supply seems fine. I tried to substitute in one of my other power supplies and everything stayed the same.

 

[Simon Anderson]

Whats the order of events? "1) plug in 2) push the switch on back 3) red light turns on and fans spin briefly 4) switch on front doesn't do anything at all?

I dunno, i was thinking some other dudes would chip in... I would have been 80% confident it's the switch, but yeah if there there's only one way to plug that in then maybe it's a really really fried MOBO. But i would still expect a MOBO to do "something" when you push the switch... i haven't had one spectacularly fail in a way that you'd still get a power light and fans doing what they would normally do, yet absolutely nothing else... i.e. if it got a massive power spike you'd think absolutely nothing would work. If it had a dodgy component or some other minor issue i'd still expect it to give you some "im broken" BEEPS. You could try replacing the switch? I'd be really really surprised if that was broken but it's cheap enough. https://www.newegg.com/Product/Product.aspx?Item=1B4-0016-000J4

But yeah I dunno, probably built 20 PC's in my time, fixed probably only 5 or so with serious hardware problems... usually swapping out memory or CPU... MOBO problems usually would be on PC's where "something really weird" would happen every now and again until you tear your hair out and replace the MOBO.... So really needs some other dudes to chip in who have more experience :/ The thing i'm not 100% confident on is if you could rely on at least getting some warning Beeps or not... could be wrong on that one. One thing i'm 99% sure on though, is that Dells have a red power light and the fans will temporarily spin up when it gets power... So I don't think that's a sign of a problem in of itself. Good luck!

 

[sorryboi]

I don't know what "switch on the back" you are talking about. There's only a power on switch on the front.
1.) I plug power cable
2.) Red light
3.) I power on PC through front power button
4.) CPU Fan spins for half a second.
Red light remains as long as the computer has power.
I can keep pressing the power on switch on the front and the same process will repeat.
There is no beep code. When i press the power on switch, it turns a dim orange for a second and then turns off. Doesn't flash.