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do i need a new power supply?

D

dcho

Limp Gawd
Joined
Apr 17, 2004
Messages
419
I have an i7 920 (whcih i plan on overclocking) and a 5970 currently on a corsair tx750. looking at some charts, the 5970 pulls nearly 400 watts at load, same with the processor which draws about 400 when overclocked. :eek: good thing i havent done anything intensive yet.

would an 850 be safe?
 
An overclocked, overvolted and adequately cooled 5970 may get close to 400watts at full tilt, but probably not without running something like furmark on it which is quite a bit more intensive than any game. An overclocked i920 won't draw anywhere near that. Either way, the TX750 will be more than enough.
 
Zero82z said:
Actually, no: http://www.xbitlabs.com/articles/video/display/radeon-hd5970_5.html#sect0
Click to expand...

That isn't credible. Many sites have shown overclocked 5970 pulling 400w. Those sites though, weren't bottlenecking the 5970 by matching it with a pentium 4.

http://www.anandtech.com/video/showdoc.aspx?i=3679&p=16

This is more in line with the consensus, and shows an overclocked 5970 at 642 watts for the system. The 5970 was downclocked to squeeze it in under the 300w pcie spec and overclocking can add 100w.
 
Well, I suppose it depends on how much he wants to overclock it, too. But he'll still be fine with that 750w.
 
I run a 650watt ps with my i7 at 4.5 with a 5870 and a 8800gt for physx and I have not ran into any problems what so ever.
 
Zero82z said:
And how many of those sites used a current shunt to directly monitor the power draw of the card? None.
Click to expand...

Try reading the review from the very site you're posting on.

The reason for these clock speed differences is quite simple. AMD’s design goal with the Radeon HD 5970 was make it perform within a 300 Watt power envelope. In order to do so, these are the clock speeds it must be at stock. Fear not however, AMD thought of us enthusiasts too. Yes, though AMD designed this video card to operate in a 300W power envelope stock, they gave it room to expand to a 400W envelope by manual tweaking! This is where it gets fun.

They also show the overclocked load hitting 540w on a system that is 165w without the card. That's 375 for the card. Sorry you got bad information and decided to spread it.
 
JCDenton said:
Try reading the review from the very site you're posting on.

The reason for these clock speed differences is quite simple. AMD’s design goal with the Radeon HD 5970 was make it perform within a 300 Watt power envelope. In order to do so, these are the clock speeds it must be at stock. Fear not however, AMD thought of us enthusiasts too. Yes, though AMD designed this video card to operate in a 300W power envelope stock, they gave it room to expand to a 400W envelope by manual tweaking! This is where it gets fun.

They also show the overclocked load hitting 540w on a system that is 165w without the card. That's 375 for the card. Sorry you got bad information and decided to spread it.
Click to expand...
The 300W and 400W numbers are from ATI, and they aren't backed up by any testing I've seen. X-bit is the only review site that directly measures the power consumption of the cards they test by themselves, so there's no way to extrapolate contradictory data from other reviews. Also, I don't see them reporting a power draw of 540W for their test system anywhere in that article, although if I've missed it feel free to point out the specific location. In any case, here you can see the raw data from their current sensor when they measured the card under load: http://www.xbitlabs.com/misc/picture/?src=/images/video/radeon-hd5970/5970_power_full.png&1=1

As you can see, they derived their numbers from adding up the power coming from both PCI-E connectors, as well as from the wires coming from the ATX power connector which power the PCI-E slots.
 
thanks for all the feedback guys. i was getting mixed replies so for a peace of mind went with the corsair tx850. that should give me some breathing room. :p
 
dcho said:
thanks for all the feedback guys. i was getting mixed replies so for a peace of mind went with the corsair tx850. that should give me some breathing room. :p
Click to expand...

You didn't get mixed replies. All of us told you the 750W was fine. They argued about a tangent. You wasted your money.
 
dcho said:
thanks for all the feedback guys. i was getting mixed replies so for a peace of mind went with the corsair tx850. that should give me some breathing room. :p
Click to expand...

The 750TX was more than enough, but the 850W certainly won't hurt. Keep in mind that a PSU is coolest and most efficient when 40-60% of its rated output (watts) is being used.
 
PC_User said:
The 750TX was more than enough, but the 850W certainly won't hurt. Keep in mind that a PSU is coolest and most efficient when 40-60% of its rated output (watts) is being used.
Click to expand...

Actually, I would imagine a PSU would be coolest when it was off and at 0% of it's rated output.:p

Doesn't hurt to have too much PSU but its money wasted. It's like buying a 15-horsepower lawn tractor to cut a 10'x10' patch of a lawn when a weed-eater or a much less powerful lawn-mower will get the job done.

I think the quality of the PSU is far more important than simply the rated watt level. Corsair TX is good.. 750 or even 650 would've been fine too.
 
PC_User said:
The 750TX was more than enough, but the 850W certainly won't hurt. Keep in mind that a PSU is coolest and most efficient when 40-60% of its rated output (watts) is being used.
Click to expand...

efficient yes, cool no. If the 750 is 75% efficient at 25% load and 80% efficient at 50% load then it will waste 62.5w at 25% and 93.75w at 50%
 
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