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How much power does my PC need?

R

Roman5

Weaksauce
Joined
Sep 3, 2009
Messages
73
Hi. It's not an urgent question, more one of curiosity. I've been using an OCZ ModXStream 700w for the past 15 months. The 8 pin atx is not supplying power anymore, the pc wouldn't post, and I've since replaced it with an XFX Pro 650w Core Edition which I fitted on friday and it's working fine. Currently about to RMA the ModXStream directly to OCZ. Love the way I have to foot the bill for shipping their faulty product back to them, but don't get me started on that, lol.

Anyway, what kind of power consumption do you estimate my sig rig is using?
There are also 2 more IDE hard drives running, a sony optiarc DVD drive, a backlit razer lycosa keyboard and of course the monitor, an LG 23" 1920x 1080. Oh and at the moment,
my thrustmaster force feedback steering wheel is connected, but since that is plugged separately into the mains and only the usb connector goes to the pc, not sure if that contributes to the power consumption in any way.
 
The computer in your specs probably uses about half of what the power supply is rated for. I would not expect you to ever reach 400W of power and most likely are under 300W.
 
Thanks mate. Wow, had no idea how little is being used. And there's me always thinking that a 500w psu would be cutting it fine.

Btw, since you seem to be XFX support, could you answer another question. I've read that a double life warranty on a particular XFX product (I think it was a graphics card) is not valid outside of the US and Canada. Is my 5 year warranty on the XFX psu also invalid to me as I'm in the UK?
 
If you ever feel like being surprised, go read up on some of the [H]ardocp reviews : P for most of them they post their test rig, and total power used. Its pretty amazing how little power you need if you dont run water pumps and 50zillion hard drives!
 
Well, I just did the Antec power supply capacity calculator that BBMW linked. I put system load and CPU Utilization both to 100% and everything in my pc I can think of, optical drive, led and regular fans, all 3 harddrives, cpu, gpu, ram, firewire and usb devices. It comes to 474w. Of course, I never really have everything operating simultaneously anyway, and even if I did, it's well under my PSU rating of 650w. Interesting exercise though.
 
I'd sell the replacement OCZ PSU or keep it for something not that important if I were you.
 
my system in sig uses no more than 300W under full cpu and gpu load!!!! Those power calculators are sometimes off, but are a good judge of what you should look at. Something to consider is the efficiency of the psu. Most psu's hit their highest efficiency ratings at 50-60% load, so you need to plan you avg. system load around hitting the psu's 50% load. So you should be looking for a psu that is right around 600-650 like you already had. My HX620 is the perfect fit for my system and 600-650 should be the perfect fit for any system using a quad, with multiple hard drives and optical drives, as well as a beefy single gpu solution. Of course you can always go with a psu that just covers your power requirements and not worry about the efficiency, however with higher efficiency the life of the psu is extended and the quality of the power supplied is better... so its really a trade-off for the extra headroom.

Also i agree, get rid of that OCZ and stick to corsair, fsp, seasonic, xfx, silverstone, or a few more brands out there. Corsair's probably the most readily available and can find a good price on one. But if i were looking at a new PSU right now i'd be looking at one of those new Seasonic X series the 650/750/850 with Gold Efficiency ratings and fully modular design (including main power, 4+4-pin 12v).
 
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Thanks ThirdLeft152. As it happens, seasonic makes the XFX psu, so that gives me more confidence in it.
 
When I bought my OCZ stealthXtream 750 I thought I got a good unit, it went bad on me. The RMA process was acceptable to me (i got a new one). I sold it and upgraded to the Corsair hx850w I have now. I'm hooked on Corsair, I've went through a ton of PSU's over the years and these guys have it right.
 
Corsair does generally have it right and I understand their philosophy on the cx series, but I think that one does go into the mediocre category.
 
650w is definitely enough. Most people overestimate how much power you actually need when it comes to psu. I think psus are more for bragging rights
 
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