Whats the worst that could happen? PSU vs Videocard

[alan671]

I had always read on the needs of a Videocard, that sometimes you need higher wattage of a PSU just to run it, one example would be in order to run Dual SLI cards you would need arount 500-even 1200 for high end cards.

I have always been wondering on what could happen if you tried to run alot of hardware, having the videocard being the part that sucks up alot of power from the PSU, with a PSU that may not look to fit the bill.

Whats the worst that could happen if you tried to run Dual GTX280s, TPIPLE 9800GTXs, Dual X4850s, etc, on a PSU that has less power for what the cards recommend?

Would something go very wrong like a short circuit? or burnt hardware? or probably nothing will happen?

 

[HOOfan 1]

If the PSU is designed badly that stuff may happen anyway...

If you try to run components requiring more power than your PSU will supply though, the system will just shutdown or continuously restart.

There isn't a single videocard out there that requires a 1200W PSU though.

 

[alan671]

I have read that, for example, their were tests that show that Dual GTX280 would need 500w + 200-300w more for everything else such as hardrives,cpu,motherboard,etc. if that was true then a PSU that is 800w-1000w could run them well without a worst scenerio happening.

Another example, that I have read recently, that in order to run 48050s in CF you need atleast 1200w, I know that is above realistic IMO, but just thinking what if you used a less wattage PSU, would something bad happen.

In the Nvidia website, the recommended PSU to run Dual or Triple SLI in any of there high end cards stated that you need 1000w+ PSU, but i also have read that some people had ran that kind of configuration with a PSU under 1000w, without a problem.

What gives?

 

[HOOfan 1]

1) The over 1200W PSU claim for the HD4850CF is Hogwash.

2) nVidia wants to leave plenty of leeway when certifiying PSUs for SLi, not to mention they don't go out and certify all PSUs.

 

[Billb2]

Yes, won't boot or will continuously reboot. The worst case scenario is when the PSU doesn't have quite enough power. It will overheat, short out and may or may not fry anything or everything.
Don't believe PSU power ratings. For example, a 500 watt PSU may put out 500 watts, but just for the second before it bursts into flames while another 500 watt PSU may cruse along all day cool and quiet at 500 watts. Then there's overload protection circuts...or lack of them.

 

[Mwing]

I just read Anandtech's latest article about Ati 4870, it shows that system power consumption loaded and idle, it shows the numbers that are very low like...

http://www.anandtech.com/video/showdoc.aspx?i=3341&p=22

say if a crappy power supply is rated as 500w, at 70% efficiency, it is like 350w right?

say I build a computer like Anandtech's test system, C2Extreme, 4 sticks of ddr3, etc etc, a highend system, with a single GTX280, it shows that idle 159.1w, loaded 313.1w

Does that mean a 500w power supply is enough for a highend computer like that?

BTW what program can show real time power consumption?

 

[HOOfan 1]

Originally posted by: Mwing

BTW what program can show real time power consumption?

None....even a piece of hardware like a Kill-a-watt isn't always reliable.

Hopefully if someone is blowing $650 on a GTX 280, they wouldn't be stupid enough to try running it on a POS power supply.

 

[Yellowbeard]

Yeah, as far as the WORST thing that could happen, if the secondary side on the PSU fails catastrophically, the resulting discharge could potentially fry every other component in your system. If you are thinking of a high end rig, don't skimp on the power.

 

[beray]

Originally posted by: alan671
I had always read on the needs of a Videocard, that sometimes you need higher wattage of a PSU just to run it, one example would be in order to run Dual SLI cards you would need arount 500-even 1200 for high end cards.

I have always been wondering on what could happen if you tried to run alot of hardware, having the videocard being the part that sucks up alot of power from the PSU, with a PSU that may not look to fit the bill.

Whats the worst that could happen if you tried to run Dual GTX280s, TPIPLE 9800GTXs, Dual X4850s, etc, on a PSU that has less power for what the cards recommend?

Would something go very wrong like a short circuit? or burnt hardware? or probably nothing will happen?

What would and could happen is explained with 6th grade math HERE --> http://forums.anandtech.com/me...id=84&threadid=2195709