PSU issue

**the Black Prince** · October 25, 2006, 02:54 PM

i'm puzzled and confused
or maybe just dumb, i admit

i'm not not a novice when it comes to putting together PC components, but i'm by no means an expert either

got myself a nice new graphics card for M2TW, which i'm happy with
installed it ok, booted it up, installed drivers, everything okeydokey and perfect

except
NVidia System Sentinal pops up and says the card isn't recieving enough power
fair enough, i go looking through the box for the supplimentary power cable, but the model i bought didn't ship with one, and i had none lying around. wandered down to maplins, bought the needed wire for £1.99, plugged it all (into the only sockets that it would fit, so thats not the issue)

and go to boot up
now instead of booting, or even turning on, with the wire plugged in, my PC now makes a whirring noise, stops, beeps twice, stops, then repeats. its like its trying to switch on, but can't.
unplug the wire, everything fine.

makes me think my PSU can't supply enough power for the new card with the wire plugged in. i checked the system reqs, the card only needs 350W, and thats what my PSU is rated for. I DID check these reqs before buying lol.

so any ideas what the problem may be. i'm dreading that it is my PSU. not merely because upgrading that would be yet more expense, but because its probably beyond my technical knowhow...

**Markas** · October 25, 2006, 04:07 PM

Unplug non-essentials such as floppy drive, cd-rewriter etc. See if theres enough power then.

**Spiff** · October 25, 2006, 04:34 PM

When they say it requires 350, theyre probably being a bit cheeky and meaning it'll run on a 350 watt PSU, assuming you have nothing else also attached, ie harddrives, CPUs, DVD-Drives etc..

What kind of Graphics card is it?

You could always have a go wth tihs little deally:

http://extreme.outervision.com/psucalculator.jsp

i wouldnt worry about upgrading a PSU though, theyre pretty cheap and easy to install since its all big chunky plugs and such

**krazykarl** · October 25, 2006, 04:35 PM

I never trust basic requirements. I have not used anything under a 400w PSU for at least 5 years. is your PSU a generic or name brand, cheapo units tend not to supply the amount of power they advertise. also keep in mind that that 350 watts is split between your mobo connector and your other connectors.

**the Black Prince** · October 25, 2006, 04:45 PM

graphics card is an XFX make geforce 7950GT PCi-Express.
i honestly have no idea what make the PSU is lol... i'll check when i open it up tomorrow to play some more... i doubt it was a cheapo unit though
EDIT, found the receipt for it, its an Akasa PSU

**Black Hawk** · October 25, 2006, 04:52 PM

A 350 watt psu is preaty weak for that type of video card, you should also check how many amps your psu has as this is more important than wattage especially how many amps the 12v has.

**krazykarl** · October 25, 2006, 08:01 PM

If you are going to get a replacement, I would recommend OCZ, thier power supplies are quite high quality. If you regularly upgrade your system, a good powersupply is like a good monitor, they last for a while, and dont change as drastically as other components.

**SPARTAN VI** · October 25, 2006, 08:12 PM

You wont catch me dead with a noname 350w PSU hooked up to a 7950GT..

I'm not sure how the nvidia's G71 refresh is with power consumption, though. What does your 12v rail look like? Anything less than 18A (and that's pushing it), on a noname, forget it...

**Hadrian** · October 25, 2006, 09:18 PM

@tBP,
Your current power supply is definately failing to produce enough power for the new VC and the rest of your system. You certainly need to get a name brand PS, as it is the main component in your system where quality is an absolute must. Cheap power supplies have too much variable/fluctuation in the 3, 5 and 12V rails, causing instability and power issues such as your having. The power bandwidth on the rails needs to be very steady and always as close to the set voltage of the rail as possible. This is only achieved with a high quality product.

As mentioned above by Krazykarl, OCZ makes excellent power supplies, as does Antec and Silverstone. That's an absolute hoss of a single GPU, so your going to need about a 500W PS with at least 18-20 amps on the 12V rail. The GPU runs off the 12v rail, and if your ever going to do SLI with another 7950GT then your going to need to get something like an OCZ 700W with multiple 12V rails....

**SPARTAN VI** · October 27, 2006, 05:10 PM

Originally Posted by Hadrian

@tBP,
Your current power supply is definately failing to produce enough power for the new VC and the rest of your system. You certainly need to get a name brand PS, as it is the main component in your system where quality is an absolute must. Cheap power supplies have too much variable/fluctuation in the 3, 5 and 12V rails, causing instability and power issues such as your having. The power bandwidth on the rails needs to be very steady and always as close to the set voltage of the rail as possible. This is only achieved with a high quality product.

And it's the most overlooked component. Lee1026 argued to the death that a brand name PSU isn't as important as I led it to be.

**the Black Prince** · October 26, 2006, 06:26 AM

yeah, i've been digging through some specs, and i don't think the ampage off the 12V rail is enough, the card recommends 20a, so guess thats the problem. well, at least i know now... and thats easily solvable. back to scan lol

**Shaun** · October 26, 2006, 07:14 AM

You need a named brand for maximum efficiency? ****! Has anyone ever heard of Winpower? I havent, but my dad says its good enough, its 650W, but it was pretty cheap, £35 to be exact, but it was off of an ebay power seller so it probably cost more in other places. Is it good enough?

**the Black Prince** · October 27, 2006, 04:28 PM

yeah, definately the power supply, only 18A over the 12V rail, and i needed 20A min...

been told by my flatmate, who works for overclockers.co.uk to stay away from OCZ though, he really doesn't recommend them for power supplies... he's getting me a decent Antec or Seasonic 450W on the cheap from the office, £20 for a PSU retail value of around £45... not bad!

**Hadrian** · October 27, 2006, 08:42 PM

Lee1026 is a couple of fries short of a Happy Meal, so I would consider the source. He's all about low end, low quality, cheap, cheap, cheap. I imagine his last build cost $28.47....
Your right SPARTAN VI, the PSU is the most overlooked component, with the greatest degrees between quality and junk of almost any component. If the PSU ain't workin, nothin's workin!