Worth trying to fix old system, or is everything broken?

Cerzi

Cerzi

Cerzi

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10 Aug 2007
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So I built a new PC a while back, and decided to build my girlfriend a computer out of old parts from my previous one. Almost immediately after installing Windows on it, the trusty old Enermax 650 died, seemingly taking out the motherboard with it.

After a lot of messing around, I've given up on that system. But I scavenged around my box of even older parts and tried to put something together for her anyway. The problem now is that I'm not really sure what bits are dead. I don't really want to spend money on a new PSU if turns out the memory doesnt work, and then the graphics card doesn't work, etc etc.

The mobo is a Asus P5k-C. The main problem is that the PSU seems to either be dead, or too weak. It's only a 430W, but its supposedly enough to power the system (which includes a 4780 gfx card).

When the graphics card isn't plugged into the PSU, the fans turn on but I get a long+3shorts beep code, which seems to indicate a video card issue. So, I plug the power into the card, but now the fans won't even start up. The CPU fan twitches ever so slightly, but that's it.

When I deseat the memory, I get the expected 1long+2short beeps, no obvious problems here.

So my question is, is the "twitching heatsink fan" a symptom of a dead PSU, or simply one that can't put out enough juice to power up the system? If so should I just grab a new PSU (500W?) and take the risk? Or am I likely to need a new graphics card as well?

Thanks a lot guys. This one's been bothering me for a while now!
 
When you say "the fans turn on" are you refering to case fans?

Test the PSU by simply hooking up a case fan, bridging the 24pin so it turns on without the motherboard and see if there is any life. Thats where I would start.
 
When the graphics card isn't plugged in, *all* fans run: case fans, cpu fan, even the gpu fan. When I plug the 2 PCI-E cables into the 4780, though, thats when no fans work, besides the cpu fan twitching ever so slightly.
 
If it was my rig I would assume that the PSU just isn't man enough for the task.

Without telling us the brand of the PSU and what the other components are (CPU etc), it's hard to tell how much "juice" the system requires.

Are you doing a barebones startup? (Hdds and optical drives disconnected). Admittedly those parts don't use much power but it may be enough to allow the system to post. Also how do you mean the gfx fan spins? Have you left the 2 aux power cables plugged in but not seated the card in the mobo?
 
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My gut feeling says that the 4870 is dragging the 12v rail/s down enough that the PSU won't pass it's internal startup test. If you have another PSU handy, and for some giggles you could connect the 4870 dual 6 pins to a different PSU and see if the system will start up. This will hopefully allow you to boot the system and determine whether it is just the PSU that is weak.

A 4870 needs a fair bit of power but you'd expect it to be ok with a quality 430w unit that can supply most of the rated power as 12v and not a duchy cumulative peak power rated unit.
 
I would agree tealc. Don't quote me but i think from memory the pci slot draws around 75 watts this is allowing the gfx cards fan to spool but once the additional power connectors are added it's drawing too much from the PSU.

A good 500W supply should cure the problem but coughing up a lil more for a 600W PSU wouldnt hurt.

Hope this helps and you are thanked properly by the gf ;)
 
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