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Power Supply Blows Fuse

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  • Power Supplies
  • Motherboards
  • Components
Last response: in Components
October 8, 2009 5:58:06 AM

So I just bought some new computer parts and after I put everything together I turned on the power supply and it blows the fuse to my room. I've tried a different cable and I've checked and rechecked the connections to the motherboard and every other power connection. What I'm wondering is that I'm using a 600w PSU and if that's enough for my machine, or is the PSU just defective. Here are the parts I just bought: ECS P55H-A(1.0) LGA 1156 Intel P55 ATX Intel Motherboard -http://www.newegg.com/Product/Product.aspx?Item=N82E168... , Intel Core i5-750 Lynnfield 2.66GHz 8MB L3 Cache LGA 1156 95W Quad-Core Processor - Retail
- http://www.newegg.com/Product/Product.aspx?Item=N82E168.... I'm still using a Radeon 1900 while I wait for the 5850 to ship. I have 3 harddrives, 2 case fans, a zalman fan for the 1900 and a cooler master cpu heatsink and fan for the core i5. Those are the only things drawing power. To reiterate, when I click the switch directly on the PSU, all the lights in my room only go out. The power supply was working before I changed the motherboard and CPU. I'm stumped. Any help would be greatly appreciated. Thanks!

More about : power supply blows fuse

a c 144 ) Power supply
a c 156 V Motherboard
October 8, 2009 7:20:15 AM

My guess is a defective PSU. What kind?
October 8, 2009 7:50:56 AM

awoglom said:
So I just bought some new computer parts and after I put everything together I turned on the power supply and it blows the fuse to my room. I've tried a different cable and I've checked and rechecked the connections to the motherboard and every other power connection. What I'm wondering is that I'm using a 600w PSU and if that's enough for my machine, or is the PSU just defective. Here are the parts I just bought: ECS P55H-A(1.0) LGA 1156 Intel P55 ATX Intel Motherboard -http://www.newegg.com/Product/Product.aspx?Item=N82E168... , Intel Core i5-750 Lynnfield 2.66GHz 8MB L3 Cache LGA 1156 95W Quad-Core Processor - Retail
- http://www.newegg.com/Product/Product.aspx?Item=N82E168.... I'm still using a Radeon 1900 while I wait for the 5850 to ship. I have 3 harddrives, 2 case fans, a zalman fan for the 1900 and a cooler master cpu heatsink and fan for the core i5. Those are the only things drawing power. To reiterate, when I click the switch directly on the PSU, all the lights in my room only go out. The power supply was working before I changed the motherboard and CPU. I'm stumped. Any help would be greatly appreciated. Thanks!


Your PSU SHOULD only be drawing 1A or less at the wall. If the PSU is a recent model with PFC, and there is a short from your MB or possibly PCI-E slot, it should just immediately shut down to save itself.

So a few quick questions...

What is the PSU?

What ELSE is on the same circuit as your room, and how large is the fuse that is blowing?

What was your previous build?
Related resources
a b ) Power supply
a b V Motherboard
October 8, 2009 1:25:21 PM

It's a 600W PSU, but nowhere near loaded - maybe guess 300W actual load, at 80% efficiency, so it probably draws maybe 375W. At 120 V AC supply, that' s little over 3 Amps.

A normal household branch circuit is fused for 15 A. Since OP says only one room's power is on this fuse, it is not a supply for many loads over a large area. So yes, the possibilities are that the PSU itself is defective and causing a short, or there are too many other loads on the circuit all in OP's room.

One way to sort out: OP should unplug a whole bunch of stuff in the room and try again. Got any electric heaters, kettles, or refrigerators plugged in? If it still blows immediately, the PSU is the VERY likely culprit.
October 8, 2009 9:23:28 PM

Thank you for your help. I'll try unplugging some of the things from the wall when I get home. I don't have anything outrageous plugged in, but I do have a bunch of little things: lights, stereo, printer, router, etc. Maybe combined with the 600w it's just too much. I'll also check the brand of PSU. As for my previous build, I have no idea what the motherboard is, that was one of my problems before. My friend gave me both the motherboard and CPU and it doesn't say ANYWHERE on the MB what it is, other than an EVGA. I tried calling EVGA and giving them the serial, but it was no longer under warranty so they couldn't help me :(  . The old CPU is an AMD dual core 4000+, that's all I can remember from the last time looked in the device manager. The old PSU is an Antec 420w. I have no idea how large the fuse to my room is... how do you check that? is it on the switch in the fuse box? Also Croc, "Your PSU SHOULD only be drawing 1A or less at the wall. If the PSU is a recent model with PFC, and there is a short from your MB or possibly PCI-E slot, it should just immediately shut down to save itself. " my computer doesn't even turn on. The MB light doesn't come on. As soon as I switch on the PSU my room fuse blows, so I don't think it's a short in the MB or I would get lights and sound for a split second I think, though maybe...

If it is just the amount of things plugged into my wall, and the comp runs when only it via the PSU is plugged in, any suggestions on how I can plug the other items in? I mean, I need my lights, my stereo and the router. Printer has no ink so that can stay off. I have to charge my phone. I doubt my landlord is going to rewire the place for me. Oh well, I hope unplugging works, at least I'll know the parts work. Thanks!
a b ) Power supply
a b V Motherboard
October 9, 2009 1:13:17 PM

To check the supply to your room you need to go to the fuse box or breaker panel, whichever it is, and read the label on the protection for your room. Screw-in fuses have a printed nuber label inside the glass front usually, but they also are color-coded. either the label or the glass of the fuse itself will be blue for 15 Amp, orange (I think) for 20A. A breaker has the number stamped and printed into its front face. If you have not already been replacing the fuse / breaker that has "popped", then someone else has - your landlord? As him / her what the circuit rating is. You'd need their help, anyway, if you looked at the panel yourself, to identify which one to look at.
a c 144 ) Power supply
a c 156 V Motherboard
October 9, 2009 1:45:40 PM

awoglom said:
The MB light doesn't come on.

If the motherboard light does not come on with power applied to the computer and the switch on the back of the PSU on, either (or both) the motherboard or the PSU is dead.

Antecs have pretty good power protection circuits. If it detects an overload or short, it should electronically shut itself down. I suspect that the short is in the primary AC circuits.

It's a really long shot, but have you tried another computer power cord?