Power Supply Unit - How Much Is Too Much?

[Silicone_Milk]

Hey guys. I'm starting to replace parts in my old pc to eventually end up with a brand new machine. The thing's about 4-5 years old and in need of an upgrade.

At the moment I have something like a 400/450w psu (can't remember off the top of my head) and it's working fine but I'm concerned about power consumption when I replace the.. everything.

I'm intending on buying 4 1TB sata drives to set up a RAID 10 config (I was originally thinking just a raid 0 config but having a single drive fail would just piss all over my day)

I have two NVIDIA 7300 GT cards that I intend on replacing with a 200 series card (for now) and eventually expanding to a DX11 compatible card such as the 480 when it drops down from the stupidly high price it'll be released at (~700.00 USD)

I'm wondering if an 850 watt psu would be a bit overkill or if I should just fork down the dough and get it since it'll give me lots of slack to expand my computer in coming years. I want this thing to last me at least the next 5 years.

Thoughts?

Thanks

[Foo]

Fork the dough. Nothing worse than getting an underspecced PSU and being confounded for years when there's random lockups and general instability and component failures.

Also, desktop PSUs are switching units, which means they'll drop to a lower consumption to meet the demand of your components. So as long as you get a good quality psu with decent efficiency rating, you won't be taking more power than your components really need.

Be careful with the power draw requirements on those drives, if they all spin up in parallel there'll be more power draw than you imagine.

[obsidian]

Many manufacturers list maximum wattage rather than suggested wattage and the two should not be confused.

I am currently running an i7 920, Gtx 280, 4 hard drives and a bunch of other stuff on a Corsair HX620W and with lots of extra power to spare.

[Silicone_Milk]

Good to know about the drives. I might end up going with the two 1TB with raid 0 and end up doing a weekly backup to an external drive so if one of the discs in the array craps out I can restore things fairly painlessly. Then I wouldn't have to worry about another two drives pulling power and adding to the temperature in the case.

This is the PSU I'm looking at - http://www.newegg.com/Product/Product.a ... 6817139011

[obsidian]

That's my current PSU's bigger brother so I can recommend that. Not sure if you'll need 850w unless you're running SLI with some ample total system overclocking, but more is better than not enough.

[Silicone_Milk]

Thanks man. I figure that 5-6 years down the road I'll probably get an sli setup once again. Especially once the DX11 cards that come out drop in price.

[SoM]

aye, dont skimp on the PSU, get something brand name at least 600+ W

i had a noname 450W and it wouldnt power my BFG 6800, bought a brand name 430 and since then i've added more shit to the PC and no probs.

[Silicone_Milk]

Cool. I'm going to go ahead and put in an order for this thing at work when I get my next paycheck.

[AmIdYfReAk]

There is a General Rule when talking about Regular Components,

a 2.5" HDD ( laptop ) takes ~2.5W
3.5" HDD = 10W
mobo = 30-50W
Fans = 1W ( max )
PCI cards = 3-5W

Then the only "wild cards" for power usage is Ram, cpu, and Video cards

quickly looking up said components online will give you the draw, and you can make your choice.

But, you also need to remember that a Higher rated power supply will be more efficient at lower level draws when compared to a PSU that is reaching its max.

so a 800W Psu is minty for basically anything you'd like to toss at it, and it should have rock solid voltages.

have fun man,

[U4EA]

But, you also need to remember that a Higher rated power supply will be more efficient at lower level draws when compared to a PSU that is reaching its max.

so a 800W Psu is minty for basically anything you'd like to toss at it, and it should have rock solid voltages.

I actually read an Anandtech article recently on this topic, higher rated power supplies are more efficient but after a certain point efficiency seems to drop. Quoting from the article:

A higher rated power supply will run much quieter if it runs at less than 50% of its rated output, but you don't want the rating to be too high or else efficiency will drop.

Also, the charts on page 3 illustrate the point quite well.

Thoughts?

The article: Debunking Power Supply Myths. Very thorough, a great read

[AmIdYfReAk]

U4EA, you're 100% spot on!

i tried not to get into much detail in my post, keeping in mind that he didn't want to spend an arm and a leg to step up to a killa-watt + PSU

There always is a point of diminishing returns, but in this case, i feel a 800w psu would give him anything he wants to do ( everything listed and more ) with the computer and not have to worry about it.

And its great to see that my Guesstimate numbers are holding water, according to that link.

Btw, Thanks for that link man! i got some nice reading materiel now

[Silicone_Milk]

Just saw a 1k watt corsair psu for a desktop. Ridiculous. I've only seen 1k watts for servers o_O

[AmIdYfReAk]

yeah, killa-watt PSU's are becoming more and more commonplace, And it could be considered a good thing when you're talking about a 3 way SLI setup with such cards like the 9800 GTX eating up 200+Watts each.

i shot a bit overboard when i built this computer, the volts move around ~.01V at times ( loaded ) but its rock stable.

Core 2 Duo E6600 ( 2.4Ghz ) @ 4ghz ( damn winter made me bring it down to 3.6ghz again :/ )
4gigs OCZ plat Rev 2 5-5-5-12 @ 2T
2X 74gig raptor raid 0
BFG 9800 GT 1gb
Watercooling
OCZ 700W Psu

[Silicone_Milk]

I can't see myself getting a 3-way SLI setup considering how they're like the PSU in terms of receiving diminishing returns.

Last time I read about it a 3rd card only added a ludicrously small increase in performance (5-10%?)

Maybe if someday they get the performance increase to 90%+ per additional card but until then, just the two will be fine

I'm going with an Intel processor this time around. I'm running an AMD Athlon 4200+ 64-bit dual core (stock). It's starting to show its age. And I've run in to plenty of oddities and issues in the past when trying to run games (Unreal 3 required some AMD driver patch to work which caused all other programs to BSOD on me)

[AmIdYfReAk]

yeah, i can agree to that...

i don't even see my self using a Sli/crossfire setup... the cost usually isn't worth the performance even with two cards.

Two cheaper cards = fast for say $350
one fast card = Just as fast, or quicker in non-supported apps = $350

for me, its not that hard of a choice in the above scenario, but to some that have WAYYY to much money, and want everything balls to the wall... buying 3 of the fastest cards and posting on the internet is key