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Computer turning on and off repeatedly with new PSU

Last response: in Components
April 27, 2013 2:11:25 PM

Recently got a new gpu (xfx hd7950) and psu (corsair hx650). When I try to turn my computer on with the new parts installed it turns on for a few seconds then off again, sometimes having the fans spin sometimes not. I took the gpu out and put the old one back and the problem continued. when I put both my old psu and gpu in it works fine. Im assuming its a compatibility issue with my motherboard (pegatron model 2A86). The computer is a couple years old now and I am wondering if I should even bother trying to fix this or go straight for a new pc.

intel I7 950@ 3.07
radeon hd6450
pegatron 2A86
4 sticks of 4gb ram totaling 16gb (unsure of who made it because it has now markings on it)
May 15, 2013 9:19:18 AM

Check the power supply output amount for the new PSU, might not have enough juice. Most likely reason is that the new PSU is broken.
May 15, 2013 9:53:38 AM

For a system using a single AMD reference design Radeon HD 7950 graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 30 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.

The Corsair HX Series HX650 (SKU# 75-001217 / CP-9020030) Power Supply, with its maximum combined +12 Volt continuous current rating of 54 Amps and with two (6+2)-pin PCI Express supplementary power connectors, is way more than sufficient to power your system configuration with a single Radeon HD 7950 graphics card.

It's not a lack of power supply capacity at all but your problem can still be caused by a defective power supply unit.
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May 17, 2013 7:52:21 AM

Did you figure anything out?
May 26, 2013 8:43:39 PM

Sorry for the late reply, I'v been having internet troubles. I sent the PSU back as DOA and the replacement causes the same problem. I assume it is more a problem with my motherboard than the PSUs because what are the chances the replacment being DOA also?
May 26, 2013 9:00:19 PM

will the new PSU and old video card work? Also check the BIOS settings for video interface. you may have something set to a static setting, when you want auto, or the setting needs to be adjusted. When installing new hardware, it's often a good idea to load standard defaults for BIOS to make sure the hardware is working, then you can try optimized defaults, or custom settings.
May 26, 2013 9:21:05 PM

The new PSU wont work with either video cards my bios is set to default.
May 26, 2013 9:23:09 PM

Was the 4-pin ATX 12V Power connector on the motherboard for the CPU connected to the power supply unit?

If the motherboard doesn't receive a PWR_OK or Power good signal from the power supply it won't power up or stay powered on.
May 26, 2013 10:18:30 PM

It was. Just as my old psu is now. But the new PSU has 2 4pin cpu connectors. Would that make a difference because I only have 1 4pin slot.
May 26, 2013 11:51:17 PM

it shouldn't. In fact, some newer MoBo's use both 4-Pin connectors as an 8-pin connector, but if yours only uses 4-Pin, you're fine. The PSU does pass a basic diagnostic? IE: PSU tester shows it is working, or jumper green line to any black line and the PSU will power on fine.