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How to tell if a PSU is not strong enough?

Last response: in Graphics & Displays
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August 23, 2007 7:49:23 AM

I've just got myself a 8800GTX (hasn't arrived yet though). My PSU (Tagan) is 480W.
Before getting myself a stronger one I want to give it a go just to see what happens. Is that a good idea or can I blow the PSU by doing this?
Is there a way I can tell that there's trouble ahead while the computer is on and I'm playing a game, say?

More about : psu strong

August 23, 2007 7:53:21 AM

I'm no PSU expert but I wouldn't just "give it a go" with a card like that.

Research online to see if it meets meets (or better yet, exceeds) the specs a 8800 GTX requires. No reason to risk anything.
a b U Graphics card
August 23, 2007 8:24:38 AM

From a bit of research, I see that that PSU has 28A (336W) on the 12V rail. The GTX uses about 11A, so you got 17A left. A C2D e6600 (you didnt specify your CPU, so I am pulling a common one out of the air) uses about 4.6A, so thats down to 12.4A. The rest of your system has (to be safe) 10-10.5A left over to run off. A typical SATA hard drive will use around 2A and a DVD burner running at full power uses around 1-1.5A (but only when reading or writing), so if you run more than one, that will hurt also. You should theoretically be able to run it, since you have a single rail PSU, but it would be cutting it close if you have more than one HDD or run an old pentium or a C2Q.

EDIT: List all your specs and that will make it easier to work out how much power you are going to need.
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August 23, 2007 8:41:50 AM

I guess you could assume that it was safe to give it a try.
August 23, 2007 8:41:57 AM

Sorry, I should have been more precise. The rest of my system is the E6400, 1 SATA HDD, 1 DVD drive.

Are the various USB devices a concern (incl. my USB hub, which is powered)?

CAN anything break by just going ahead with it? I can't imagine that any of my components will go into melt down. The PSU might blow a fuse though, I suppose....
August 23, 2007 9:39:53 AM

You should be fine, even if it didn't have enough power for your 8800GTX it would clock down to prevent the unexpected.
August 23, 2007 9:43:09 AM

Would I experience a very distinctive lack of performance in that case, or could a lack of power go unnoticed? I will be running games to push the card to the limit (Bioshock at 1920x1200)...
August 23, 2007 11:16:53 AM

Naujoks said:
Would I experience a very distinctive lack of performance in that case, or could a lack of power go unnoticed? I will be running games to push the card to the limit (Bioshock at 1920x1200)...


Believe me if it clocks down you'll know, yes you would notice a very distinctive lack of performance. Your PC might even reboot or turn itself off because a lack of power. I have never heard of a case where having a not enough power caused damage.
August 23, 2007 11:30:32 AM

Thanks guys, I will just go ahead with it and see what happens. On Monday I will know more and will let you know.
Cheers now!
August 23, 2007 11:36:25 AM

Naujoks said:
Thanks guys, I will just go ahead with it and see what happens. On Monday I will know more and will let you know.
Cheers now!


Let us know how it go's and good luck mate.
August 28, 2007 10:05:44 AM

UPDATE:

Ok, I just stuck it in (and what a big one it is!), fired it up, all seems to work ok. Bioshock framerates still not great (at 1920x1200, ah well), 3DMark06 somewhere around 9000, which is average I suppose.

So, everything seems to be working just fine. Guess I'm lucky!
August 28, 2007 10:09:45 AM

I remember this thread :) 

I'm not nearly lucky enough to own an 8800 GTX but I'm pretty sure 9000 is WAY low on 3dmark 06.

Please don't fry your card.
August 28, 2007 10:17:58 AM

I've compared my 3DMark results with those of others with similar system setups. The highest mark I can see of someone is 9400, so not that much more than my own...
August 28, 2007 11:04:32 AM

My bad - I missed you're running at 1920x1200.

PS - you should always indicate you're not using the free version.
August 28, 2007 11:18:22 AM

No no! I'm running BIOSHOCK at 1920x1200. 3DMark is the standard free edition.
I've just installed the latest Beta Geforce drivers, and now I get very good framrates in Bioshock as well (around 50-70), so I'm very happy, really...
a b U Graphics card
August 28, 2007 11:30:21 AM

You can use this site to calculate your power requirements. It is always better to use the actual power consumption figures from the hardware you have though. This site gives an acceptable range figure. Always add 20% safety margin to their figures. You do not want to running at 100% of your power capacity.

http://www.extreme.outervision.com/psucalculator.jsp
August 28, 2007 11:47:58 AM

When i first got my 8800 gts i put iit with a 400w psu and it worked perfectly. I upgraded to a 550w 2 months later just incase something happened.
!