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Motherboard wont start with new psu

Last response: in Motherboards
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August 20, 2011 12:57:06 AM

Hello,bought a new psu for old motherboard,(abit kt133a.) Motherboard will not start. Motherboard does work with old PSU,(250watt!) New PSU (600watt,) works with a newer motherboard,( Asus kt400,!) What's the deal?
a b V Motherboard
August 20, 2011 1:21:15 PM

Was the Mobo originally from a prebuilt like Dell?
Have you plugged everything in correctly?
start at the beginning,
20+4pin
4pin for cpu
any plug for your gfx card (make sure its a pcie line and not the 4/8pin cpu one)
front panel connectors to mobo all in correct place?
you should be able to boot from there,
if still having issues, it may be that your mobo has proprietary connectors, which you dont want hehe
there is a troubleshooting guide over in homebuilt section if you want pictorial help, its a sticky up at the top
Moto
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August 20, 2011 6:30:52 PM

Motopsychojdn said:
Was the Mobo originally from a prebuilt like Dell?
Have you plugged everything in correctly?
start at the beginning,
20+4pin
4pin for cpu
any plug for your gfx card (make sure its a pcie line and not the 4/8pin cpu one)
front panel connectors to mobo all in correct place?
you should be able to boot from there,
if still having issues, it may be that your mobo has proprietary connectors, which you dont want hehe
there is a troubleshooting guide over in homebuilt section if you want pictorial help, its a sticky up at the top
Moto



Not from a Dell. Motherboard is : Abit KT7a (KT133a chipset.)
Only what PSU I use makes a difference.
There is no 4 pin for CPU...not intel! Is AMD athlon.
No proprietary connectors.
Been doing this for years,
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August 20, 2011 9:44:22 PM

....SOLVED......I forgot to check that "new" PSU had a -5 volt line for the ISA slot, (KT7133a had one.) Motherboard is looking for -5 volts that is not there on the new PSU. Looking around the web, I see others have had the same problem. Hmmn,..what will the enthusiast do these days? Look for ancient PSUs? Guess I could solder a -5 V regulator somewhere, etc.
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a b Ĉ ASUS
a b V Motherboard
August 20, 2011 10:06:31 PM

Get one of thoes 4 AA cell bartter holders, stic 4 rechargable NiCd batteries in it (4 x 1.25 = 5.0 Volts) Read lead to ground, black lead to -5 V pin. No sure how much current is drawn, But a DVM connected to measure current, and you have the I. If low enough may last a long time. A small 5 or 10 volt relay can be used to remove power when PC is powered off

2nd option: get a small 2.5 Amp brick made for usb Hubs and wire that in. same-same for relay, or Switch off wne PS is off.

3rd option -5 V reg = 7905 and tap off of -12V. Need series resitor to keep 7905 from over heating probably.
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August 21, 2011 2:10:42 PM

..Thanks for the input. Third option, tapping off of -12V sounds best. Will test it out.
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