nV vs ATi power consumption article Part 2@X-Bit

[DAPUNISHER]

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EDIT: repost? I don't care the PSU questions keep on coming so....

 

[JBT]

Good article. Can't say I have seen that one yet. Though I have seen one similar with basically the same results.

 

[Marsumane]

So the 5950 takes more watts to power. I wonder why the ultra has the need for 2 molex connectors then? I mean why didnt the 5950? And if u think about it, i dont see how the 6800u could use THAT much more power even when overclocked more to justify the need for another molex.

 

[jiffylube1024]

Wow, impressive o/c results there with the X800Pro and 9800XT.

I read that article before but it's a great read - very informative.

All anyone really needs to do is load up the ninth page and look at the summary to get the gist of the article.

It's impressive how ATI has finally caught up to Nvidia in keeping their idle power draw so low; comparing the 9800Pro/XT to the 5950, the 5950 does a much better job conserving power in idle mode, while the 9800 Pro is still up there.

It's interesting to see how much more wattage the top-end cards use compared to the 'value' cards (5700, which is a decent indicator of other value cards)

 

[jiffylube1024]

Originally posted by: Marsumane
So the 5950 takes more watts to power. I wonder why the ultra has the need for 2 molex connectors then? I mean why didnt the 5950? And if u think about it, i dont see how the 6800u could use THAT much more power even when overclocked more to justify the need for another molex.

I think the extra molex is a precautionary measure, just like how the early P4 northwoods often didn't 'need' the extra +12V connector (and some boards omitted it), it was better for stability.

 

[Lonyo]

It's the 12v line that means you need the extra molex.

Most people don't have a clue about their PSU's.
A generic 500w PSU is probably going to have the same 12v line as a 330w Antec PSU, probably 16~18A.
XBit says you need high 12v for the 6800U.

Most PSU's skimp on the 12v, so you need to ensure you can get good 12v power to the card, and molex connectors allow this (2 coming straight from the PSU means more chance of clean 12v power I would guess).

As shown, the GeForce 6800 Ultra doesn?t practically take any power through the AGP slot. The total consumption of the card on the 3.3v, 5v and 12v lines that go through the AGP is less than 5W. But the card consumes as much as 48.91W in the Burn mode through the 12v line of the additional power connector. The current in this line is 4.22 amperes, which is rather much even for the Molex 8981-04 connector.

(I wrote my comment before seeing the XBit labs comment saying almost the same thing).

Personally I think an Enermax woul dbe best for a 6800U, as they have either dual 12v rails, or a very high 12v rail (much higher than Antec's, at similar wattages).
330w Antec has 18A 12v rail, IIRC. The 350w Enermax has a 26A or thereabouts 12v rail, and the 320w Enermax has 2 rails totalling 24 A IIRC.

 

[Dman877]

It looks like the high end parts all use more volts to achieve the higher clocks. Look at the 6800U vs 6800GT, 9800Pro vs 9800XT, 5900U vs 5950, etc. All the slower cards, even when clocked past the faster cards, use less power then the faster cards at stock. Makes me think flashing your bios to the faster card would help your oc in most cases...

 

[jiffylube1024]

Originally posted by: Lonyo


Personally I think an Enermax woul dbe best for a 6800U, as they have either dual 12v rails, or a very high 12v rail (much higher than Antec's, at similar wattages).
330w Antec has 18A 12v rail, IIRC. The 350w Enermax has a 26A or thereabouts 12v rail, and the 320w Enermax has 2 rails totalling 24 A IIRC.

Yep, this is one of the main reasons I always recommend Enermax first and then Antec second.

I had an older 350W Enermax with 18A or 20A; new ones have ~26A and the 460W Enermaxes have 35-36A.

 

[jrphoenix]

Originally posted by: Marsumane
So the 5950 takes more watts to power. I wonder why the ultra has the need for 2 molex connectors then? I mean why didnt the 5950? And if u think about it, i dont see how the 6800u could use THAT much more power even when overclocked more to justify the need for another molex.

The article spoke about how the Nvidia cards (6800) received almost all their power through the molex and didn't use hardly any from the AGP slot. I'm assuming the ATI cards use more of the available AGP power. I'm not sure why Nvidia wouldn't do the same?

 

[jiffylube1024]

Originally posted by: jrphoenix

Originally posted by: Marsumane
So the 5950 takes more watts to power. I wonder why the ultra has the need for 2 molex connectors then? I mean why didnt the 5950? And if u think about it, i dont see how the 6800u could use THAT much more power even when overclocked more to justify the need for another molex.

The article spoke about how the Nvidia cards (6800) received almost all their power through the molex and didn't use hardly any from the AGP slot. I'm assuming the ATI cards use more of the available AGP power. I'm not sure why Nvidia wouldn't do the same?

Because... That's just what they'd be expecting.

Maybe it's less taxing on the motherboard? Maybe PCI-E offers less power through the slot and this is a design in preparation of PCI-E. Who knows?

This would explain why the top 6800's need 2 molex connectors, though, while the 5900's dont.

 

[Ackmed]

This is about the 5th one of these I have seen. Every other has had different results from each other. Makes it hard to try and believe any certain one.

 

[Gamingphreek]

How are the OCZ powerstream PSU's rails and 12v like? I heard they are incredible PSU's and am looking to pick one up, however just outof curiosity i would like to know how it stacks up. Also how would a 5900XT do in those tests. Less power than the 5900U but more than the 5700U but about where lol?

-Kevin