Are Mega-PSUs truly necessary? [From GT200 Thread]
- Thread starter suryad
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i seriously wish you the very best of luck with tri-sli and even 500w
- go for it
RotFL
Actually a system with 2 HD3870X2's can peak just a bit over 500W depending on what other components are used
Did you actually read the frigging link before you posted?!
aaronspink
Veteran
800W at the wall. Lucky for us proper power supplies are rated in DC OUTPUT. Assuming 85% efficiency (about the best you can get) you are looking at DC draw of 700W leaving a very comfortable 150 watts to spare (since the common PSUs around that output are all ~850W devices).
Oh, and BTW, that power draw is with 3x Ultras in SLI not GTX.
And no, it won't degrade it faster. Unless you are trying to run it fanless, it will just result in more noise, generally the EXACT same noise as a bigger supply. Considering the components used in the 850/1000/1200 W power supplies are pretty much the same with a few swapped components generally related to limiters etc being the differential. The basic components, caps, layout, boards are generally the exact same thing. The only thing that generally changes is the power mosfets and they are the least of your reliability concerns.
Aaron Spink
speaking for myself inc.
aaronspink
Veteran
yes, they peaked at 800W AC. Power supplies are rated and tests to DC. For top end power supplies 800W AC is ~700W DC. For normal good quality power supplies 800W AC is ~660W DC.
Any reputable 800/850W PSU can do tri-sli just fine.
Aaron Spink
speaking for myself inc.
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Okay, those in the thread I linked must have not setup their systems correctly and Nvidia recommended 1100w PSUs for those...
My 850w Silverstone has a 140mm fan on it. It's noise level never goes above my case fans levels.
I'd rather take jonnyGURU's opinion on running a PSU too close to it's max shortens it's life as a rule to buy alittle more then "just enough".
The problem comes into play when people buy a cheap PSU after spending thousands on the rest of the parts and wonder why it's not stable.
Not all are created equal and it takes researching most won't do to find a quality PSU.
My 850w Silverstone has a 140mm fan on it. It's noise level never goes above my case fans levels.
I'd rather take jonnyGURU's opinion on running a PSU too close to it's max shortens it's life as a rule to buy alittle more then "just enough".
The problem comes into play when people buy a cheap PSU after spending thousands on the rest of the parts and wonder why it's not stable.
Not all are created equal and it takes researching most won't do to find a quality PSU.
Actually a system with 2 HD3870X2's can peak just a bit over 500W depending on what other components are used
Wonder what the figure's like with QuadFX Athlons...
aaronspink
Veteran
Nvidia recommends an 1100w PSU to be on the safe side because there are a lot of crappy PSUs out there.
Running at PSU at 80% of rated isn't really pushing it, especially when the PSU was designed for a range of operating points from 800-1200 watts. Any decent quality power mosfet is subject to the same bathtub effects of any other piece of silicon, which means that if it works for a week, it will work for a decade+ (assuming they aren't using underspec'd parts). The primary issues for reliability are connections and electrolytic components. Everything else is effectively solid state and won't degrade except on timelines long enough not to matter. You still have random mode failures but for the PC market those don't matter.
of course they aren't created equal, but assuming you are smart enough to buy a reputable power supply they are all pretty much in the same ballparkl.
Quite honestly, I'm still waiting for us to go to 24 or 48 volt internal distribution instead of this crappy 12v stuff. Would up the overall efficiency quite a bit.
Aaron Spink
speaking for myself inc.
no .. not at all; i know better and don't bother with "theoretical nonsense" under best conditions
i OWN HD2900XT crossfire - it is in my rig as my 8800GTX cooked this week -and 700w simply won't cut it in a PRACTICAL situation[period]
why don't you check out nVidia's *approved* PSes for Tri-SLi insteading of posting silly theoretical links from tech websites?; There are no 500/600/700/750w approved for Tri-SLi [unless i missed something] i have real practical experience with it and 850w is decent for my system
"I'd rather take jonnyGURU's opinion on running a PSU too close to it's max shortens it's life as a rule to buy alittle more then "just enough"."
- exactly! My OCZ's only problem is "ripple" near its rated power; and old-skool connectors .. it will get replaced by a 1,100w i am buying later
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Really? Tell that to my buddy's wife running a Q6600 @ 3GHz and SLI o/c'd 8800 Ultras (MSI factory o/c). Killawatt readings never surpassed 420W during a recent LAN party in which her machine was running the Windows Folding @ Home SMP client (100% CPU utilization on all cores at all times), acting as game server for whichever game we were currently playing (not a dedicated server, she played the whole time too), as well as acting as file server for our ahem files cough for up to 12 clients.
Those numbers don't add up. We see super-linear power consumption scaling in Bioshock by adding a 3rd card, and the same in Crysis with the 2nd card. Why has no other website replicated this?
For the record:
X-bit > Anandtech.
Edit: sorry, no more PSU posts from me.
It's not theoretical, dude.
You're basically talking about a subject without proper education on said subject.
Want to know what i think ?
Nvidia recommends high-Wattage PSU's for top-of-the-line GPU's because the chance that they also have a high-ampere rating are better.
They've been doing that at least since the NV40 days.
And that's the key point if you want stability, Amps.
If you're a novice user with cash to burn, you end-up purchasing PSU's with plenty of Watts of power, neglecting the amp rating.
But if you're a "connoisseur" i'm sure you can find a low-Watt/high-amp model that is perfectly capable of powering even the latest GPU's in multi-card setups with stability to spare.
Most "sane" (those without 15k rpm drives RAID arrays, 150W TDP server CPU's and lots of 10W FB-DIMM's, etc, etc) Quad-SLI or Crossfire-X setups barely reach 500W sustained load at any given moment.
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I don't understand your reasoning. P = VI, in DC so they are in phase.
There is obviously a linear relation between current and watts, so what is your point again?
I used as reference those who did the reviews when TRi-SLI was the new kid on the block and posted screen shots of 800-900w loading on air cooled setups.
Back on topic, thankfully from the rumors it seems the GT200 won't draw as much power as the old G80 chips. I never looked at running Tri-SLI for heat reasons. Even though the new cards should run cooler, SLI is all I'd consider out here in the highdesert.
Back on topic, thankfully from the rumors it seems the GT200 won't draw as much power as the old G80 chips. I never looked at running Tri-SLI for heat reasons. Even though the new cards should run cooler, SLI is all I'd consider out here in the highdesert.
It's not a technical question but one of marketing. That's the entire point of this debate, which those on "your side" seem not to grasp yet.
Overall wattage rating is derived from a combination of peak sustainable amperage delivery on *several* voltage rails. The +12V rail being the most important of these, with +/- rails for both 3.3V and 5V being present as well.
The problem here is that PSU manufacturers tend to spec their cheap units with more power on the 3.3V and 5V rails than is necessary, and not nearly enough on the +12V. This is why graphics card manufacturers are forced to recommend end-users purchase PSUs that may be huge overkill for their system configuration and usage scenarios.
Example:
I recently put together an E8400/8800 GT rig to tide me over as a gaming system until Bloomfield Nehalem or (fingers crossed) Shanghai's desktop derivative. When shopping for PSUs, I wanted to stay around $100 because I didn't want to cheap out, but I knew that anything more than that was likely to be overkill. So I looked at a lot of PSUs in that price range, in between 430-600W. What I found was disturbing. A lot of these "600W" PSUs actually had less amperage on their +12V rail(s) than my old Dell "305W" PSU (dual 18A rails). I finally settled on the Corsair 550 VX model which has a single 41A +12V rail, and have been very satisfied with it.
LOL, so much for not posting about PSUs anymore.
Perhaps a thread split is due?
Perhaps a thread split is due?
