Alan2273 Posted December 30, 2005 Report Share Posted December 30, 2005 I have just started to put together a computer for a friend.The motherboard, processor, memory & graphics card are second hand.I put the mobo in (The processor, fan & memory were allready in place on the mobo) and connected the graphics card, connected the monitor and fired it up and on the monitor it said the ATI card needs an extra power connector so I pressed the power switch to shut it down, located the extra power connector on the graphics card, connected it and turned it back on and nothing except a clunk sound from the PSU.The case is a Jeantech (which is brand new) with there own make 300watt PSU.I have used a multimeter to check the main connector to the mobo and only 2 sets of pins show any output, 1 shows 3.4 volts and the other shows 4.9 volts.Every time I switch it on the PSU just goes clunk, is there a reset switch on the PSU.Any help appreciated.A bit more information.The motherboard is an ASRock KT74A, the processor is an AMD 2600, The memory is 512mb 2700 (333) and the graphics card is an ATI 9700pro. Quote Link to comment Share on other sites More sharing options...
-pops- Posted December 30, 2005 Report Share Posted December 30, 2005 300W isn't very much for a modern system. You'd be better with more power capability.Regarding the lack of output, switched power supplies don't function properly if they aren't fitted with a load so, if you're testing with your meter on bare pins, not connected to anything else, you won't get anything like a true reading of the output.The clunk sound you are hearing may well be the PSU shutting down to protect itself. Quote Link to comment Share on other sites More sharing options...
Alan2273 Posted December 30, 2005 Author Report Share Posted December 30, 2005 300W isn't very much for a modern system. You'd be better with more power capability.Regarding the lack of output, switched power supplies don't function properly if they aren't fitted with a load so, if you're testing with your meter on bare pins, not connected to anything else, you won't get anything like a true reading of the output.The clunk sound you are hearing may well be the PSU shutting down to protect itself.Why when it worked the first time , would it then shut down to protect itself?.If I just connect the PSU to the mains and turn on should the PSU start with nothing connected to it ?. Quote Link to comment Share on other sites More sharing options...
-pops- Posted December 30, 2005 Report Share Posted December 30, 2005 Why when it worked the first time , would it then shut down to protect itself?.Because you say at the second power up you had connected another item to it.Regarding your second question, I have known some PSUs to remain inert if power is applied but with no load on the output. Others do produce some output though but not as they are supposed to. Quote Link to comment Share on other sites More sharing options...
r4may Posted December 30, 2005 Report Share Posted December 30, 2005 Why when it worked the first time , would it then shut down to protect itself?.(-pops- @ Dec 30 2005, 16:20) Because you say at the second power up you had connected another item to it.Could be an Overload causing PSU shutdown Try Calculating the required Power here:-http://www.jscustompcs.com/power_supply/ Quote Link to comment Share on other sites More sharing options...
Alan2273 Posted December 31, 2005 Author Report Share Posted December 31, 2005 Could be an Overload causing PSU shutdown Try Calculating the required Power here Just out of interest I checked the power requirement for what I had got connected and it only came to 168 watts so the PSU must be duff. Quote Link to comment Share on other sites More sharing options...
Alan2273 Posted December 31, 2005 Author Report Share Posted December 31, 2005 Brought a new power supply and it is up and running. :biggrin: Quote Link to comment Share on other sites More sharing options...
bvw Posted January 1, 2006 Report Share Posted January 1, 2006 Brought a new power supply and it is up and running. :biggrin:Well done :biggrin: Quote Link to comment Share on other sites More sharing options...
woodchip Posted January 1, 2006 Report Share Posted January 1, 2006 As I told you on PCA, If you try starting a PSU without it connected to the Motherboard You will blow it. AS it's a Switching PSU and needs a Load for it to work. You have blown the PSU if that's all the volts you get. Quote Link to comment Share on other sites More sharing options...
Alan2273 Posted January 1, 2006 Author Report Share Posted January 1, 2006 As I mentioned on PCA I had the motherboard connected both times, so I did not blow it by switching on with nothing connected. I brought a new one and had my brother who is an electrician check the faulty out and he said it was a protection circuit that was faulty. Quote Link to comment Share on other sites More sharing options...
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