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What happends if I draw too much power?

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March 17, 2010 9:59:37 AM

Hello.
Does anyone know what actually happends if I attempt to draw more wattage from my psu than it is built for?
I'm getting a new graphics card in the door any day now, and according to the psu calculator I'm going to be 220 watts short.
How serious is that to be taken?

System specs:
GA-EX58-UD5 motherboard
i7-920 @ 3.8Ghz (1.375v)
1x 1TB wd green drive
1x 1TB hitachi 7200rpm 'performance' drive
6x 120mm fans (4 arctic fan 12 pwm, 1 arctic fan 120 and 1 silverstone fn121)
1x ide dvdrw drive (sony I think)
1x sapphire 4870
1x club 3d 4870x2
620W corsair HX psu

psu calc result is available here in print form : http://www.opel.cc/i7.pdf

What'll happen when I plug the extra graphics card into the mashine and start some load?

More about : happends draw power

March 17, 2010 10:01:11 AM

more detailed specs can be seen in my profile by the way - with the one graphics card currently in use.
a b ) Power supply
March 17, 2010 10:21:21 AM

Corsair is a great brand and that psu has been made by Seasonic (very good manufacturer). Anyway, if you attempt to draw more wattage from the psu than it is built for...:

1. If the difference is big, the psu doesn´t work and you can´t turn on the computer
2. If the difference is not big, the computer turn on but the problem is that the psu is working very hard (full load) so you are shortening the life of the psu.

If the difference is about 220w, as you say, the computer won´t turn on.

As you can see in this review, the max load for it is 746W:

http://www.hardwaresecrets.com/article/371/9
Related resources
March 17, 2010 11:19:05 AM

746W ? that's enough to run the system with 25% aging and no overclock.
As it is now, my cpu's underclocked to 2.3ghz with only 2 cores active and no ht most of the time, as I rarely need the full potential. Suppose not overclocking isn't too bad so long's the psu can then survive :) 

http://www.opel.cc/i7-2.pdf <-- power draw without overclocking

Hope my unit's as good as the tested one :) 
a c 243 ) Power supply
March 17, 2010 1:04:30 PM

neiroatopelcc said:

http://www.opel.cc/i7-2.pdf <-- power draw without overclocking

Hope my unit's as good as the tested one :) 

That's not power draw, it's a psu wattage reccommendation.
The HX620 is an excellent psu, but you shouldn't rely on the overload tests to determine the amount of load you put on it.
Your video cards alone have tha capability to put an 85- 90% load on the psu ( according to it's labeled rating ) , you should seriously consider purchasing a higher wattage unit.
March 17, 2010 1:07:35 PM

ye I know I should do that, but if I can get away with not doing so I will.
alternatively I'll have to add a second cheap psu - better than buying a new one :) 
March 17, 2010 3:29:43 PM

Never get a cheap psu.The psu is a bit you should never go cheap on. Get a good make eg (ocz) get a brand name.ocz are good and they dont cost much if you got the money money get a Corsair


March 17, 2010 3:41:44 PM

Corsair 950W TX Series PSU - 78A 12V Rail


OCZ Z Series 1000W Modular Power Supply Unit
a b ) Power supply
March 17, 2010 4:52:04 PM

I would definitely get a bigger PSU with the data you have. If you draw too much power, Your PC will most likely shut off. When this happen, it may not do anything, but it COULD seriously damage your hardware. Its not worth cutting it too close, plus the closer you are running to the MAX your PSU can handle, the faster it will deteriorate, and eventually it won't be able to run your rig anymore.
That Corsair is good, but if you are really gonna be pushing what the calculator is telling you, then its not gonna like it. I'd give it a good buffer and get something in the 950+ wattage range.
March 17, 2010 6:57:49 PM

I suppose you're right about it being too small.
Thing is I didn't exaclty 'go cheap' on the psu. I got the HX620 as a replacement for a broken 680W thermaltake (at my request) some years ago, and had a thermaltake butterfly before that. Haven't gone cheap since the day my q-tec 550w almost set fire to my flat back in the pentium 4 days.

As for the ocz suggestion - no way ! I built a system as a present for my parents last year using an ocz power supply (i7, 4890, sas drive, green drive,bd & dvdrw drive) and the power supply is possibly the loudest thing in their house! what's the point of spending 100€ on silent fans and a lian li case if the powersupply wakes up the neighbors. So I'll stay away from ocz thank you.

Think I'll dabble in a dual psu setup instead of replacing my trusty corsair.
a b ) Power supply
March 17, 2010 7:13:40 PM

Yeah. Those Dual GPU cards are rough on the PSU, and the 4870's on their own aren't light on it either, especially when you are OCing your CPU and running a bunch of fans and stuff. Good luck though- should help you out in the end:-) Definitely better than blowing a PSU and having it wreck your CPU and MOBO with it like I did a couple builds back.
March 17, 2010 7:16:00 PM

Actually the last time I blew a board was back in 2001 when I'd imported a bunch of stuff from ocz (called ocz store back then).
The voltmod on the abit board went bad and killed cpu and the geforce 4. Was a sad day - but a rare thing to see.
a b ) Power supply
March 17, 2010 7:20:27 PM

Yeah- Mine was just a crappy PSU, was rated plenty high, but deteriorated and blew- big bang, smoke, the whole deal. It was pretty crazy and I had to basically build a whole new machine.
!