Replaced dodgy PSU, then Graphics card burnt

March 29, 2011 at 13:15:53
Specs: Windows 7, AMD Phenom Quad Core / 4gig RAM

I was wondering if someone can help. I've just bought all the bits required to build a PC. With help I've put it all together and it was all working fine for a couple of days.

I was in the middle of a game and the PC just shut down. I opened it to check all the cabling and nothing seemed to be hanging lose. Tried a different power cord and it all started for about half a second before cutting out again.

I've managed to get a different PSU and installed that into the PC. Both are 700w.

On turning it on with the new PSU everything started to run, but a component on the Graphics Card (SLB4 and 5) started to glow and then smoke. I turned off immediately.

As these are all new bits I'm trying to understand what the problem is.

Could a dodgy PSU damage the Graphics Card and cause this when more power is supplied. Could the Graphics Card of been faulty? (not sure why the original PSU didn't work though)
Or could the motherboard be at fault here?

I've now removed the Graphics Card and it seems to run okay, I've not had the confidence to put the old PSU in to see if that works now without the Graphics Card as I don't want to cause any more damage.

If anyone has any ideas please let me know.

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March 29, 2011 at 13:39:41
You need to post detailed specs of all the hardware including model numbers.

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March 29, 2011 at 13:52:35
Original PSU was a 700 NorthQ Silent Ghost NQ775-700
Replacement is a 700w ThermalTake. Not sure of anymore more than that.

Graphics Card - 2GB Palit GTX460 SONIC
CPU - AMD Phenom 2 X4 995 sAM3 Black
Motherboard - Gigabyte GA-MA770T-UD3

Let me know if you need any more details.


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March 29, 2011 at 14:27:52
What are you using for graphics now? Did you have both PCI power connectors connected to the graphics card?

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March 29, 2011 at 14:33:21
Where in the world are you located and what is the local power voltage and frequency?

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March 30, 2011 at 01:01:17
I'm on the UK mainland. So it's 230v and 50hz.

Yeah, made sure both PCI power connectors were plugged in.

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March 30, 2011 at 01:19:18
Another thing I've found out is that the new PSU has overload and short circuit protection, where as the replacement doesn't.

So could it of been a dodgy Graphics Card that caused the new PSU to shut down. The old one without the protection just powered everything and burnt out the dodgy Graphics Card?

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March 30, 2011 at 05:36:20
The original power supply has 4- +12V rails. Each rated at 16A. If you look further the four rails have a total rating of 520W. However, If you add up the wattage for the 4 rails individually by multiplying 16A x 12V = 192W per rail x 4 = 768W. Obviously the four rails are not capable of delivering the full current on all four simultaneously.

Your Thermaltake may be a single +12V rail unit with a 57A rating on that rail.

What this means is that the first power supply might not have been able to supply adequate power to the card.

Multi-rail PSUs have fallen out of favor for this reason.

You didn't answer #3.

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March 30, 2011 at 05:45:28
I've not had it up an running properly without a graphics card. Though I've just got hold of an old ATI HD 4350 600m DDR2 DVI HDMI VGA card which I am going to try tonight, to see if this works.

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