PC not powering up - Antec 1650b & Asus K8V-X SE motherb

[may_hem1]

I've just fit together the component of my new PC and when I press the power button nothing happens. Can anyone help?

Here are the components of my new PC:
- Antec 1650b case (came with a 350w power supply),
- Asus K8V-X SE motherboard,
- AMD Sempron 2600 socket 754 (own sink/fan),
- Corsair 1Gb DDR ram,
- Maxtor 300Gb hard disk,
- ATI Radeon 9250 video card,
- Ebuyer firewire/usb PCI card.

When I plug the PC into the mains, then flick the power switch on the back of the case to the on (1) position then a green light comes on on the motherboard.

Then when I press the power button on the front of the case nothing happens. The power supply doesn't make any noise, the power supply's fan doesn't spin, the CPU's fan doesn't spin, the case fan doesn't spin, the hard disk doesn't power up.

I guessed that the motherboard must be receiving power as the green light comes on. I wondered if it was the power switch cable which connects to the motherboard, so I took out all of the LED cables & the speaker cable and left in just the "POWER SW" cable and the "RESET SW" cable. Tried to power on but again nothing.

I think I should mention that the power supply has a 24-pin cable for the motherboard, but the ASUS motherboard has only a 20-pin socket. However it plugs in just fine, leaving 4 of the pins hanging unconnected off the end of the socket. Could this be a problem?

There's also a 4-pin cable coming from the power supply which I plugged into a matching socket on the motherboard. I think this is the Aux Power cable and I think I read on the web that this must be connected for the Asus motherboard to power up. Well I've connected it but no power up.

Can anyone help me?

Thanks,
May

[diver]

1. Make sure you have a CPU, 1 stick of memory, a video card, keyboard, in addition to the power leads attached to the MB. Do not plug anything else into the motherboard. Make sure all jumpers are in the default position.

2. Try shorting the pins on the motherboard that connect to the power switch on the front panel of the case. This will test for the possibility of a bad switch.

3. If #2 does not work, take the system somewhere and get the power supply tested, if you do not have another system to plug it into.

4. If the power supply checks out, it might be a bad motherboard.

[FollowTheMusic]

Ive had similar problems that I still haven't solved 100%. My very, very strong (but unconfirmed) suspicion is that it's the motherboard.

If you have a multimeter or voltmeter, you can do at least a sanity check on the power supply as follows: set the meter to DC V, ~20V range. Turn the PSU switch on. Find a spare 4-pin Molex connector from the PSU. Touch the COM lead on the meter to either of the two center Molex pins (black leads). Touch the other lead to either of the outside pins. One should read 5V, the other 12V (forget which is which). If it's pretty close, that should be good enough.

The fact that the motherboard lights up means it's probably a bad motherboard. Another thing to check is that there is no short to ground. That means making sure no unused leads are in contact with the case, and especially that the motherboard is not touching the mounting plate at any point.

Other than that, it's hard to be certain without test equipment. Try getting a spare PSU or mobo to swap out. But yeah, it's probably the mobo.

Edit: Sorry, forgot to say the PSU has to be running somehow to test it. Either wire it to an old mobo, or see http://www.duxcw.com/dcforum/DCForumID3/447.html for hotwiring instructions. Be warned that this could conceivably damage your PSU, though very unlikely. But wise to jumper it, test, and turn it off as quickly as possible.

[andyb]

Thats good advice from Diver.

Adding to Point 2. Check the manual, use a screwdriver and make contact with the 2 pins for the power switch (do NOT make contact with any other pins). If you dont want to do that just yet, wire up the reset switch instead and try that. BTW the switches do NOT have a correct position, either way round will work.

Another thing to try, is to take take out both of the motherboard power connectors and check that everything is OK, then re-connect it, also make sure the extra 4 pins on the 24 pin connector is NOt touching anything on the board.

Yet another thing to try is to disconnect the PSU from everything (mains included), get a paperclip and bend it straight, then bend it round into a "U" shape, then connect the GREEN wire on the 24pin connector to ANY BLACK wire (double check that its correct before plugging in and turning on your PSU).

If the fan goes, your power supply is probably OK, (you can only test it further is you happen to have a voltmeter). Do NOT leave your PSU running un-necessarily as it wont do it any good.

If your PSU fan starts you can rule that out.

Re-seating your CPU and RAM is also worth trying, if that does not work, that the mobo out of the case, and try it OUTSIDE of the case on the bag your motherboard came in, if it works you have a short, check the IO sheild is OK, and that the mobo standoffs are OK.


Andy

[diver]

Sometimes a motherboard can be shorted by an extra metal stand-off. That is, one of those things is screwed into the case somewhere where it is not needed. The MB makes contact and voila, a short.

I did not know that green wire trick. Learn something new every day.

[may_hem1]

Thanks for your advice. I'll take it step by step.

I'm a little cautious about the paperclip trick as I don't want to damage my PSU. What's the difference between a voltmeter and a multimeter? Are they expensive? It sounds like a good way to test a power supply. If I go to a high street electronics store, what features should I look out for when buying either a voltmeter or multimeter?

This is the first time I've had a PC completely refuse to even start, and for a second I wished I hadn't thrown Dell's regular junk post away. But only for a second. Building my own machine is far more satisfying. I just find it frustrating waiting for parts to be delivered. Does anyone know a shop in central London which has component prices not far off internet prices, with a decent faulty returns policy? If each item is only a couple of pounds more expensive then I'm willing to pay that. Then if something goes wrong I can go straight back and ask for a swap, without lengthy RMA delays.

Well I'm going to be up late tonight as I won't get any sleep until I've tested all I can. Wish me luck!

May

[Tibors]

... if that does not work, that the mobo out of the case, and try it OUTSIDE of the case on the bag your motherboard came in,...

No, don't put it on the bag.

[aztec]

For what its worth....I just got a 1650B a couple of weeks ago....ran a 2400+ XP for a few days....then 1 day it wouldn't turn on.

the PSU died.

curiously, nothing overclocked or even remotely close to be conisdered a "power hungry" component.

the PSU....just simply died after a week!

[may_hem1]

For what its worth....I just got a 1650B a couple of weeks ago....ran a 2400+ XP for a few days....then 1 day it wouldn't turn on.

the PSU died.

curiously, nothing overclocked or even remotely close to be conisdered a "power hungry" component.

the PSU....just simply died after a week!

Ooh, don't say that..
I hope mine doesn't die..

Thanks for everyone's advice. My machine is working now.

You know what the problem was?

I put the power switch cable on the wrong pins. Doh! I don't know how, as I checked it like 10 times.

Thanks for your help,
May

[HaloJones]

I don't know what PSU you got with your 1650B but I've now had two deliveries of the Antec SLK3700BQE with the Smartpower 350W and both PSU have been DOA. Love the case but hate the PSU.