PSU question

TheGamingGeneral

TheGamingGeneral

TheGamingGeneral

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Hello, am often hit with the notion, that, people with these ludacris claims of needing 1600W psu's for sli systems are just nuts. However, I am actually wondering if, minus the cost of buyin the unit, running it is that much more expensive.

Specifically, I have found a modular PSU that I am very interested in, that costs £88, not cheap, but get what you pay for I suppose. It is a 620W corsair I think. However, after looking round, I found a 1000W fully modular psu for £100, just £12 more, and 380W more powerful if my maths serve me right.

But I am wondering, would the 1000W cost me, nearly 40% more to run, or does it not work like that? I have been told the psu's only draw what they need, or, to put it another way, a 1000W psu, doesnt nescesarily mean it costs twice as much to run as a 500W.

Thanks a lot for any help :)

Martyn
 
A PSU will draw what is necessary for the system to run so for a given system which has say a 350w power requirement then your PSU will take ~350w regardless of whether the PSU itself is rated at 500w or 1kw. There are efficiency bands so it isn't strictly as simple as that if you are being absolutely exact but to all intents and purposes it makes no odds aside from the extra capacity built in.

Do remember that not all PSUs are created equal so it might be worth specifying who makes the 1kw PSU you are looking at.
 
I don't know a huge amount about Ultra PSUs although what I do know suggests they are fairly decent and JonnyGuru rates that particular PSU very highly, I'd say go with it with the possible exception if you would be loading the PSU very lightly as it seems not to be quite so happy with that oddly. :)
 
Hi GeneralD, if you don't mind me asking, what sort of system are you looking at running?

The reason I ask is because I doubt very much that you will need a 1000 wattage power supply unit. I would personally choose the Corsair HX 620W ATX2.2 Modular SLI Compliant PSU , it is a superb power supply. Now, even though the Ultra X3 1,000W is only £12 more and you get an extra 20 amps on the 12 volt rail, I can't say I have heard much about the particular unit and what also concerns me is the price of it, it's seems fairly cheap for such a high wattage power supply.

However, reading through a couple of reviews, one by Anandtech and the other by Johnny Guru, they seem to both suggest they are pretty good power supplies overall. I would still suggest (providing your not going to be running a system that consists of a massively overclocked Quad core, Quad SLI with a dozen hard drives) the Corsair HX 620W ATX2.2 Modular SLI Compliant PSU. It is honestly one of the best power supplies on the market at the moment. :)
 
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Fire Wizard said:
Hi GeneralD, if you don't mind me asking, what sort of system are you looking at running?
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Sure, the system I had in mind would be built in two teers.

Initially, it would be

E6750
Gigabyte P35 DS3L
8800 GTS 512mb
2GB Corsair Dominator PC8500
Silverstone TJ07/09 case

To be then upgraded around summer time to something along the lines of:

XFX 790 ultra
2GB DDR3 RAM
9*00 G** x2
Q9450
Blu ray drive

I was under the impresion that, eventhough the high end of the two would still not fully tax the PSU, I wasnt so sure the 620W would be up to powering a, say Quad SLI setup, if I indeed went for that. N am not so keen on spending £88, and then a further £100 less than three months later. I'd rather pay once and then be done with it.

Martyn
 
I'm still not convinced SLI is ever going to be worth it. I went for a 620 which gives me enough scope for different things without being stupid.
 
InkZ said:
I'm still not convinced SLI is ever going to be worth it. I went for a 620 which gives me enough scope for different things without being stupid.
Click to expand...

Well I mean, the ultra is only £8 more, and, if it isnt more expensive to run, I cant see what is dumb about it. It does everything the corsair runs, just as cheaply (apparantly), and, gives me the as much adding potential as I could ever want. As far as I can tell, theres no down side to it. Which was why I put this thread up to make sure I am reading it right :)

Martyn
 
Hello GeneralD, to give you an idea of the sort of power requirements a similar system that you have specified will be needing: :)

The Nvidia 9800 GX2 consumes around 200 watts under load which equates to 17 amps. Two Nvidia 9800 GX2 would equal to 34 amps. Now, if we add an Q9450 running at stock into the equation, the processor will be consuming around 100 watts which would equate too 9 amps. Add a couple of hard drives rated at one amp each and then some for the extra head room, this system will be pulling around 48 amps on the 12 volt rail.

Now, the Corsair HX 620W ATX2.2 Modular SLI Compliant PSU is rated to have 50 amps on the 12 volt rail and would actually probably run the above system fine under real world tasks such as playing games, video encoding etc.. However, it would leave very little headroom for adding any extra hardware components in the future and if you were also looking at overclocking the graphics cards.

Now, the way I use my system which isn't particularly taxing to say the least :p, I personally wouldn't have any problem running the above system on the HX 620W ATX2.2 Modular SLI Compliant PSU. However, if someone was looking for a power supply unit to run a system like the above, I would have to recommend the Corsair TX 750W ATX2.2 SLI Compliant PSU which has 60 amps on the 12 volt rail, which would be perfectly sufficient.

Like the rest of the entire Corsair power supply unit series, the Corsair TX 750W unit is nothing but superb.

I think the below comment by the review site Hardware Secrets really sums up the quality of the Corsair TX 750W power supply unit:

Hardware Secrets said:
This unit also has all the basic stuff everyone is looking for nowadays: high efficiency, active PFC, excellent cooling solution, enough power to feed high-end video cards, five-year warranty and the best of all: it can really deliver its rated 750 W at 50º C. Not only that. During our tests we could pull up to 900 W at 45º C. So you will be basically buying a 900 W power supply paying the price of a 750 W one. What is sweeter than that?
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Source - Corsair TX750W Power Supply Review.

You may also be interested in reading a couple of other reviews of the Corsair TX750W unit, one by Johnny Guru and the other by Bit-Tech. :)
 
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