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I've asked a few questions (which you can view in my profile) regarding an old Gateway GM5474 (mostly) stock PC, It has been throwing kernel panics and just general non-responsiveness at random. Thanks to SU's help I've found I had a bad stick of RAM, and a mostly functional computer!

However, now I come to you all with this next question:

My video card has been dropping off the bus, It causes the machine to look as though it has stopped responding but it still reports, acts, and responds to user information over ssh and vnc. (YAY!) I have removed the video card and am currently running off on-board graphics but I've purchased a new video card that can be ran on the old hardware and upgraded the memory

Should I be upgrading to a higher wattage psu? OR How can I tell that my PSU is not putting out the correct amount? (and causing the video card to drop off the bus)

The only changes made have been a video card and 4GB RAM and three Hard Disk Drives.

Video card replaced by: Nvidia Geforce 9400GT (a less demanding card)

HDDs: WD 500GB 5400RPM(2X) and WD Green 1TB 5400RPM

Stock Info:

Athlon 64 X2 3GHz
400W PSU
NVIDIA® GeForce® 6150SE chipset
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Tell us what you have as a current power supply... – Ramhound Sep 28 '13 at 22:30
@Ramhound Link to specs added and very basic info from link added to question. – Cole Busby Sep 28 '13 at 22:35
I can't find a reference to an 8400GT; is that correct? I see an 8400GS and an 8500GT. In any case, the 8400GS uses 71W max, Nvidia says, but a 400W PSU would seem marginal with what you have, i.e. 3 hard drives etc. That system came with 1 drive and a 400W PS, so you can figure that adding 2 more drives & a different video card is likely too much for it. You can usually check the PSU voltages in the motherboard BIOS on most systems. – Debra Sep 29 '13 at 0:11
@Debra Re-looked at the box and made the change, 9400GT. – Cole Busby Sep 29 '13 at 0:33
OK, that one has a max power draw of 50W and the minimum spec for a PSU is 300W -- given that your system came with the 400W and one drive, and you probably also have connected devices, I'd suggest going to a 550W PSU or better. The disk drive requirements will vary by model, but give yourself lots of breathing room. Also I can't find anything helpful on the ECS BIOS setup, but from what I recall of ECS boards I've used, it likely allows you to check PSU output. – Debra Sep 29 '13 at 0:37
up vote 3 down vote accepted

I will take a stab in the dark, but from the base configuration, the three hard drives (which I presume are not SSD) and now a new power-hungry video card, I would upgrade the PSU to cope with all of that.

Normally, OEMs give you a PSU with the minimum to work, so it wouldn't be surprising if your PC suddenly shutdown while you are playing a game or doing another GPU intensive task, while your drives are spinning their lives away.

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The rig is not really a gaming machine anymore. It used to be but is now a XBMCbuntu Media Center Server. – Cole Busby Sep 28 '13 at 22:55
@BraiamUpdated the question to better assist your stab. – Cole Busby Sep 28 '13 at 22:56
@ColeBusby I wasn't able to find the specifics, but based on cards of the same family (9400) the minimum is 400W, to that you should add up your 3 HDD, and also that you suspect some fail I said yes, replace the PSU. – Braiam Sep 29 '13 at 4:51
that is why I accepted your answer. – Cole Busby Sep 29 '13 at 4:54

Measure the wattage used. with a power meter. like enter image description here

As for a bad PSU. I have detected bad Power Supplies before, by checking them with a multimeter. Including ones that were once ok and then not so.

If the voltage is not stable, keeps changing, then change the PSU 'cos bad PSU.

If out of range voltage eg the red wire is not near 5V then change PSU.

I read of the technique called backprobing in Scott Mueller's UGRP, the PSU had molex connectors.

An electronics expert I spoke to said that a PSU can still be bad - with voltage fluctuations and a multimeter not pick it up, but if a multimeter does pick it up then it's really bad.

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