Power supply question for CF 6950's unlocked

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palaciav

Weaksauce
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May 18, 2011
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So, ordered an MSI Twin Frozr 2GB from Fry's online when they had their deal earlier in the month. About a week passes by with no confirmation email or CC charge from Fry's and I end up down at the Wilsonville, OR branch and see them there for $270.49 open box. Since they were still on the website for $259.99, get them to give me a new in box model for that price and get it home to successfully unlock it. Next day, I get a confirmation email from frys.com, a credit card charge and another card shows up at my doorstep. :eek:

After a lil bit of hemming and hawing, decide my finances aren't really hurting and to spoil myself with a bit of Crossfire fun! :D

I'm using an older Seasonic 650 W power supply, can't remember the model off hand. It's at least 5 years old now, used it for a couple years in an AMD64 X2 6000+ build, then again in my current i7 920 C0 for close to three years now. So, current system specs are:

Core i7 920 C0 (currently stock, planning to OC at least to 3.6)
EVGA x58 3 way SLI board
3 x 4GB G. Skill 1600
4 x spinner 7200 rpm HDDs
1 x DVD-RW
2 x Twin Frozr II 6950's shader unlocked (assuming best case scenario of 2nd card unlocking as well)
1 x SB X-Fi Titanium

Would a 5 year old Seasonic 650W handle what I'm planning, or should I invest in a newer, maybe higher wattage model? And recommendation on a new power supply if so?
 
As solid as Seasonics are, I think you're going to have to go for a 800W PSU. Even more so if you are planning on OCing.
 
If 12v amperage on that unit is above 50A I think you should try it out, chances are it will work;)

Name your budget and your preferred shopping location/s.
 
Preferred shopping location will likely be Newegg, perhaps Amazon if their shipping estimates aren't longer than a couple weeks.

Budget isn't a super huge concern so long as I can get similar longevity... let's say keep it under $150 and see where that gets us, shall we?
 
A 750 watt is safe with some headroom. Most good 750 watt power supplies run for less than $100.
 
palaciav said:
Preferred shopping location will likely be Newegg, perhaps Amazon if their shipping estimates aren't longer than a couple weeks.

Budget isn't a super huge concern so long as I can get similar longevity... let's say keep it under $150 and see where that gets us, shall we?
Click to expand...

You don't need to spend 150$;)

Again, check your PSU and let us know what kind of 12v amperage it offers, is it single rail or not?

As far as suggestions go, Rosewill Lightning 800W @ 150$, there are no better 800W units(or above) inside that budget.
 
I will have to check it when I let off of work, but I am certain it is not a single rail PSU. I believe it has 3 12v rails, but we shall have to see.
 
I actually bet it will work

stock clocks on everything
 
That 650 will be kinda tight. You'll be pushing it real close to the edge if you overvolt and overclock, maybe even over the edge.

Tsumi is right. Grab a good 750w PSU and you'll be just fine.

I like the new XFX PSUs. Good value.
 
I'm running almost the exact same setup on a 2 year old 650w Antec Earthwatts. You should be fine.
 
I believe the cards each came with one Molex to PCI-E adapter. If not I have a couple somewhere. So I'll be fine doing Crossfire even once I start overclocking the CPU?
 
palaciav said:
I believe the cards each came with one Molex to PCI-E adapter. If not I have a couple somewhere. So I'll be fine doing Crossfire even once I start overclocking the CPU?
Click to expand...

Yeah, as long as you don't go mad with the voltages on those two cards.
 
52amp max on your PSU between all 12volt rails
figuring the 80% rule of thumb, that's 41.6amps

Your cards can pull 450watts alone, 37.5amp (that's based on 75watts from the motherboard, and 75watts per 6 pin connector, each card has two, if your cards have the 8pin, that's rated to 150watts per connector)

Personally I'd get a new one
I like Corsair myself, and recommend this one
CORSAIR Professional Series HX850
850watts, modular and you can read the review here on [H]
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011
 
Spudsdude said:
52amp max on your PSU between all 12volt rails
figuring the 80% rule of thumb, that's 41.6amps

Your cards can pull 450watts alone, 37.5amp (that's based on 75watts from the motherboard, and 75watts per 6 pin connector, each card has two, if your cards have the 8pin, that's rated to 150watts per connector)

Personally I'd get a new one
I like Corsair myself, and recommend this one
CORSAIR Professional Series HX850
850watts, modular and you can read the review here on [H]
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011
Click to expand...

...

/facepalm
 
Tsumi said:
...

/facepalm
Click to expand...
I hear ya. And yes I might think the same thing, but maybe my thought process on the power supply is abit different then other's here.

Would a 750watt be fine, sure, could you power the whole thing off a 550watt, it would be close, but if it's a good one it's possible. Would I try to power it off a 6 year old 600watt power supply, if I was broke I might try it, but If I was spending my hard earned cash on a new power supply I would want to be forward thinking about it.

Unlocked cards, so power use goes up abit, and yes it's alot less then what the power circuits can supply. A tweak here, a voltage bump there to get rid of the last little dips in the latest game, and then a touch more to see how high ya can go. Idle drives spin back up to the highest load (initial power draw), cpu pegged for testing and overclocked, you bump the cpu abit higher and need better cooling, a simple fan swap from a .36amp fan to a high speed 2.0amp fan (or that Delta 4.0amp monster, this is [H] after all), a crazy amazon.com deal lands you another 6970 for $200, these things do happen.

What do you do when the next system change comes along. You can't just add a few bucks to the power supply to give it more headroom.

It's all subjective, if you go off the max that can be supplied to the card, you'll be in good shape regardless of card choice.

That's just my way of thinking, of all the things in the computer the power supply seems like it should be the last thing to save a few bucks on, and yes I'm guilty of doing it more times then I can count. It's also one of the few parts that tends to migrate to new builds.

After 18+ years of building and tweaking these things I always think of what the power supply will power now, what's coming next and what changes to the system will be made. If it's a tight budget, and the system won't be updated/upgraded yes you can certainly get away with less of a psu, and for a lot of standard users it's how it's done.

So yes, I agree with your /facepalm and disagree with it as well, at the same time. Dont' ya just love computers.
 
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