Computer won't post

[Going to Cali]

Computer won't post - IT's the PSU but I'm VERY confused!?

Hi,

My little bro and Dad are trying to build a PC and they're getting stuck. Their components are

Asrock 4CoreDual-VSTA
Conroe 2160
2gb geil ram
Akasa Ultra Quiet 400W Paxpower Active PFC ATX2.2 PSU - Black Nickel
9800pro

They've plugged everything in and when they power up all lights are on and fans spin etc. However they don't get to a bios screen. I've asked them try the ram sticks, but this didn't help. even putting no ram in didn't give errors beeps. Interestingly, they only connected one large power cable to the mobo, with an extra 4 pin in the fans begun to spin but then stopped and nothing happened. any ideas?

 

[Going to Cali]

My Dad' plugged in a sata and an ide I believe, but surely that isn't the problem when it's not getting to the bios?

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Update, my bro's tried the psu with the previous comp and same symptoms. with large power it spins fans but no bios, with extra four it does nothing. Sounds like psu to me, but also can you use an atx 2.2 psu with an older style mobo? atx 2.0?

 

[Going to Cali]

Ok, it's definitely the PSU. My brother's just tried his Tagan TG580-U15 580W ATX2.01 Easycon SLi Compliant Modular Silent PSU and it works fine. He's said it's because there's a difference between the 4 pin cpu power cable on his atx 2.01 and the atx 2.2 psu. Something to do with there being a triangle and a square head on the same row. I'm sorry this is a bit unclear, but can anyone clarify?

 

[Going to Cali]

Thanks for everyone's help. Eventually worked it out. My Bro & Dad were trying to put the 4 spare pins from the mobo connector into the cpu power socket. They had to break up the 8 pin connector into 2 fours. They won't make that mistake again!