[sivispacem]

QUOTE (oysterbarron @ Tuesday, Jul 24 2012, 09:56)

Sorry sivis but what bit didnt you read when i said it wasnt running on a 700 watt one and you suggest a 550 would have done?

I would suggest that it was more to do with it being a crap, cheap or damaged PSU, rather than the actual wattage.

With:

4.4GHz i5 2500K @1.65v (absurdly high voltage but done as a demonstration)
Top-spec motherboard
4 sticks DDR3
3 regular and 1 SSD hard drives
1 Blu-Ray R+ and 1 CD-RW+ drive
Coolmaster V10 CPU cooler
2x120mm and 2x140mm fans
4 additional USB peripherals
10% capacitor ageing
90% load

Xtreme Power Supply calculator says ~640W

QUOTE (oysterbarron @ Tuesday, Jul 24 2012, 09:56)

The problem started when he put a new screen on and was solved by a better psu

There is absolutely no reason why adding a second screen would draw any additional power compared to running a single screen on a system at load. I would argue that the two are completely unconnected.

[yojo2]

QUOTE (sivispacem @ Tuesday, Jul 24 2012, 12:41)

Xtreme Power Supply calculator says ~640W

Actually, calculators also recommend way more powerful PSUs than necessary. I'd say that Xtreme calc is the best calc out there, but still a bit off.

QUOTE (oysterbarron @ Tuesday, Jul 24 2012, 10:56)

And yoyo that is nowhere near the recomended wattage for his card  its not even the recommended for mine and mines a mid range card from a year or so ago.

That's because GPU manufacturers' recommendations are a bit off as well. Simply because not all units that are labeled, for example, "700W" are identical in terms of power they can deliver. Aside from build quality, one 700W PSU might have e.g. 700W on 12V rail (and that's where GPU and CPU gets power from), while some other might have 600W or less. A good example is OCZ ModXStreamPro 700W, which has 552W on 12V rail... while OCZ ZS 650W also has 552W @ 12V, even though it's labeled as a 50W less powerful unit. Moreover, OCZ ZT 550W has 540W@12V, so it's basically just as powerful as ModXStream and ZS.
Thus, even a good quality PSUs can differ by a good couple hundreds of watts, while in theory they should have the same power.

Also, nVidia recommends at least 550W PSU for my GTX470 (which consumes more power than HD5870)... while in reality the whole rig doesn't consume more than 300W (exactly: 300-320W with inefficiency losses included; measured with power meter when playing Crysis 2 @ max details in Dx11).

This post has been edited by yojo2 on Tuesday, Jul 24 2012, 11:29

[oysterbarron]

QUOTE (sivispacem @ Tuesday, Jul 24 2012, 10:41)

QUOTE (oysterbarron @ Tuesday, Jul 24 2012, 09:56) Sorry sivis but what bit didnt you read when i said it wasnt running on a 700 watt one and you suggest a 550 would have done? I would suggest that it was more to do with it being a crap, cheap or damaged PSU, rather than the actual wattage. With: 4.4GHz i5 2500K @1.65v (absurdly high voltage but done as a demonstration) Top-spec motherboard 4 sticks DDR3 3 regular and 1 SSD hard drives 1 Blu-Ray R+ and 1 CD-RW+ drive Coolmaster V10 CPU cooler 2x120mm and 2x140mm fans 4 additional USB peripherals 10% capacitor ageing 90% load Xtreme Power Supply calculator says ~640W QUOTE (oysterbarron @ Tuesday, Jul 24 2012, 09:56) The problem started when he put a new screen on and was solved by a better psu There is absolutely no reason why adding a second screen would draw any additional power compared to running a single screen on a system at load. I would argue that the two are completely unconnected.

Well from experience with my ati card when i have a second screen attached it boosts the tickover mhz core clock from 150mhz to 500mhz on the desktop.so i would imagine that is pulling more wattage than normal. Also ive always thought that the reason the recommended wattage for cards was inflated was due to the possibility of the person running multiple monitors.

[yojo2]

This is true that power consumption raises when the card outputs image to multiple monitors. The difference is pretty low though, about 10-20W.

[sivispacem]

QUOTE (yojo2 @ Tuesday, Jul 24 2012, 13:24)

This is true that power consumption raises when the card outputs image to multiple monitors. The difference is pretty low though, about 10-20W.

It won't boost power draw in a card beyond the same draw at maximum load with a single monitor, would it? The reason it draws more when it you have two screens at low load is because its having to render two images at a time, but that just doubles (or theoretically doubles) the speed at which 100% load is reached- it doesn't increase the power draw beyond 100%, does it?

[yojo2]

This depends on the card I'd say. Most often there is a slight raise of power consumption even at full load. But as I said, it's pretty insignificant.