What Happens if your PSU doesn't give you enough power?

[Konut]

Heres my situation. I just bought a new computer with the following specs. It cost me about $750.

3800+ X2
1 GB DDR2
250 GB hard drive
19 inch widescreen LCD
Integrated 6150LE graphics (For now)
300W power supply

I want to buy a new graphics card, something along the lines of the X1950pro. I was going to buy the X1900GT, but then the pro came out which seems to be slightly better. My problem is that i just spent $750 on a new computer system, and I really don't want to spend that much more. Originally i thought i was just going to have to buy the graphics card for a little less than $200, but now i realize that there is a good chance i'll have to buy a new PSU as well.

My question is: What would happen if the graphics card tries to draw more power than my system can supply? I ask this because according to this review http://techreport.com/reviews/2006q3/radeon-x1900gt/index.x?pg=9 and a few other reviews, a system with the x1900GT will never call for more than 300W of power even under load.

Do you think i can get by with a 300W power supply even though the card "says" it requires 400W?

If you don't think so, what would the down sides be to buying a cheap 430W power supply like this? http://www.newegg.com/Product/Product.asp?Item=N82E16817171007

Thanks for help in advance.

 

[tool_462]

Personally, along with about 98% of the forums, I would tell you to not risk using the crappy PSU or buying a new "crappy" PSU. It may work, but if it fails, you could lose a lot more $$ than the $30 it costs you to get a better PSU.

FSP, Enermax, Seasonic, Antec, Cooler Master, OCZ, Mushkin, Silverstone, PC Power & Cooling, Thermaltake...others I'm sure I missed, are all good brands.

The Cooler Master you linked appears to be fine, I don't see any reason it won't work just fine and stable as any other, except it's ugliness

 

[Konut]

Ok, i'll probably end up buying that power supply. I have a few more questions though.

Does anyone know why this review and many others say that the System power consumption under load is less than 300W of power for almost every single slot graphics card? It seems to me like most graphics card companies just say to buy a monsterous power supply so they don't get sued if someones computer gets fried, even when the cards don't need nearly that much.

Again, heres the review.

http://techreport.com/reviews/2006q3/radeon-x1900gt/index.x?pg=9

Question 2:
What makes the more expensive power supplies better than the cheap power supplies with the same wattage. I know it must be something, but i'm a newb with power supplies so i have no idea.

Question 3:
One person has said the cool master i listed above should be okay for my needs, but can other people validate that. Again, i want to spend as little money as possible, but in the same breath, I don't want my computer to blow up after a few months.

Thanks again.

 

[enewmen]

Is there any problem with getting a oversize PSU?
Such as, if I get a 700w PSU and my system is only using 400w, then only the power needed comes out of the wall. (Not the full 700w.)
I am thinking of getting a PSU I don't need to upgrade for a long time.

I did read your 101 sticky.

 

[enewmen]

I am not a pro. But from what I read, the expensive PSUs have more STABLE power (as well as features). Such as, if your 12v rail is jumping from 11v to 13v, that can do VERY BAD things to your hardware. Where a exensive PSUs will lock in within 5% of the spec and never change under idle or full. (has enough amps) Such as locking in at 12.1v and never changing.
Don't skimp on the PSU, all computer parts require stable power and the PSU will probably outlive your motherboard.

 

[enewmen]

Nevermind, I found it. Thanks.

Keep in mind that having a PSU that exceeds your system’s needs will not hurt anything. The PSU will only provide the power and current the system needs. Find yourself a balance. You want to have a big enough PSU that can support any future upgrades you may want. At the same time you don’t want to be spending a lot of money on a PSU you don’t need.

 

[flooder]

Yup... just get a new Power Supply. At least 550W. It is in the sweet spot and cheap.

 

[tool_462]

I appologize, I didn't check the amperage ratings on the Cooler Master. 19A (rated) will probably not cut it, as Amperage is more important than total Wattage when regarding power draw. Look for something with total 12V Amps in the 30ish range, some PSU's have more than one 12V rail and will displace 30A across two rails (Ex: 16A on 12V.1 and 14A on 12V.2)

 

[enewmen]

I actually had my eye on the Aspire Iceberg 680w.
http://www.newegg.com/Product/Product.asp?Item=N82E16817148030
Add some lights to my future clear case.
Seems like a high-quality card. (yes/no) ?

 

[enewmen]

My only options are blue, green, or pink.
Thanks for the feedback on the +12v rails!

 

[jaguarskx]

Does anyone know why this review and many others say that the System power consumption under load is less than 300W of power for almost every single slot graphics card? It seems to me like most graphics card companies just say to buy a monsterous power supply so they don't get sued if someones computer gets fried, even when the cards don't need nearly that much.

Again, heres the review.

http://techreport.com/reviews/2006q3/radeon-x1900gt/index.x?pg=9

The answer is based on the components inside the PC. Besides the GPU, the most power hungry component would be the CPU. In the review the X6800 was used. According to Xbitlabs.com, that CPU uses 66w of power. Compare that to the older and slower Pentium D 820 which uses 145w of power. Big difference.

Link:
http://www.xbitlabs.com/articles/cpu/display/core2duo-shootout_11.html