750 watt PSU enough?

currob

currob

currob

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Hi, just used the extreme psu calculator and it says minimum psu needed is 662 watts. This is quite close to my limit on current psu so I would appreciate any thoughts/comments. My upgrade will take my system to:

Asus M5A97 pro ATX 970/950 / [email protected] / 2 x HD 7970's / 2 x 4Gb DDR3 / 3 x 120mm case fans (LED) / 2 x 80mm case fans (LED) / 2 x 120mm radiator fans / 1 x watercooling pump / 1 x ssd / 1 x 5400rpm hdd / 1 x fan controller / 2 x cold cathodes / 1 x bluray RW / 1 x card reader / 4 x usb devices / 1 x pci satellite card.

My current PSU is ocz zs 750 watt 80+ bronze

Is this psu enough in your opinions?

Thanks
 
The ZS has 650W (54A) available. One of my gripes would be the lack of PCIE connectors. So it is in fact a 650W gaming PSU.

I've recorded a usage of 450W running unigine on my rig below at the plug. Best you could do is get a power usage monitor (£15) and check it for yourself. Anything above 600W, and I would consider a bit too close for comfort. I think it's enough, just about.

If your PSU starts making fan noise it means it's working hard, so that's also a good indication. Bit hard to hear over the rest of the system under stress though.
 
yes, the system is a little noisy so probably wouldn't hear any change in psu fan speed. I've never reached the limit on a psu before but assume i would have random crashes under load if i did?
 
The PSUs have safety features (Active PFC for load distribution, over-current, over-voltage, but that's for the mains getting iffy). They would shutdown the computer immediately, or reduce the power to the graphics cards, meaning either instability, lock-ups, crashes, loss of performance (some GPUs throttle when the power is insufficient).

A good PSU should not blow up and take the components with it. However, you are still relying on its safety. And computers don't like to be shut down abruptly (hard drives especially, with their huge data caches getting corrupted). Running a PSU close to the limit is a big risk imo.

I was wrong about the PCIE connectors, appears it has enough of them.
 
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hmmm, i might not take the risk then, maybe it's time to go up to a 1kw psu, wasn't planning on the expense but the zs 750w should sell on ebay :)
 
I'd have thought for day to day you'd be fine, but there again it really does depend on how long you have it running at those levels. If you are approaching the limits of the PSU you will:

1. Start to run less efficiently
2. stress the PSU. The PSU is RATED at 750 Watts, but there's usually a safety margin built in.

If you are indeed being constrained by the PSU, then you will see that your performance will be being choked or held back vs where you theoretically should be - you've not mentioned any symptoms of that with your rig.

I'd urge you to buy the best PSU that you can afford if you are still going to purchase one, and buy one that is greater than you will need now, or in the foreseeable. 1kw+ would certainly be the way to go, but make sure you pick up a decent brand, such as Corsair etc. It goers without saying that a good 750W psu will always be better to have than a rubbish 1kw one.

Sorry if this sounds like egg sucking - too many people scrimp on PSU's and motherboards but will spend more on a GPU and wonder why they can't achieve a stable overclock...
 
powerconsumptionj.jpg


Keep in mind that overclocking (especially on GPUs) does up the power consumption. I would tab at around 550, 600W intensive gaming, full overclock.
 
Thank you, I appreciate the advice and your time in providing it. I will go for a decent psu as I will probably add more to the system in future. OCUK have a good price on the Corsair 1050watt and ocz zs 1250watt psu so I will take whichever one is in stock when I go into the shop next week.
 
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