Author Topic: Total newbie asks about power supply  (Read 2602 times)

Gordon

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Total newbie asks about power supply
« on: January 06, 2015, 01:29:02 PM »
Yes, I am a total newbie to computer-building. But I think this is a great little build, and I am definitely going to go for it. Thanks for posting it. Question: Just for the hell of it, I went to pcpartpicker.com  and started inputting your parts list. Problem: within a few minutes the site informed me that the case's 90W power supply was insufficient for the CPU, motherboard, SSD, etc. I thought "whoa, what's happening here?" So what is happening? Obviously, you have built this system and tested it, and I trust your experience more than I trust the algorithm at pcpartpicker. Still, I'd like to know your reaction.

By the way, I plan to use ubuntu linux 12.04 LTS, which I have on a thumb drive. Does that make sense?

Thanks again for putting together this mini ITX build!

Ari Altman

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Re: Total newbie asks about power supply
« Reply #1 on: January 07, 2015, 07:05:12 AM »
Yes, I am a total newbie to computer-building. But I think this is a great little build, and I am definitely going to go for it. Thanks for posting it. Question: Just for the hell of it, I went to pcpartpicker.com  and started inputting your parts list. Problem: within a few minutes the site informed me that the case's 90W power supply was insufficient for the CPU, motherboard, SSD, etc. I thought "whoa, what's happening here?" So what is happening? Obviously, you have built this system and tested it, and I trust your experience more than I trust the algorithm at pcpartpicker. Still, I'd like to know your reaction.

By the way, I plan to use ubuntu linux 12.04 LTS, which I have on a thumb drive. Does that make sense?

Thanks again for putting together this mini ITX build!

Great question! I've seen the PSU information on PCPartPicker, and I believe they added it because their original algorithm just found the cheapest prices, and didn't actually inform buyers of whether parts would work together. I definitely think the enhanced algorithm is a good step, but ultimately, it's just based on manufacturer recommendations or approximations for product categories. And these really can't get at the nuance of how much power parts actually use. A good PSU algorithm will ALWAYS overestimate the power required, because that's the only safe thing to do.

The guides on The Tech Buyer's Guru recommend power supplies based on experience measuring power draw using various system configurations. We can't test them all, but we've tested quite a few. And in the case of the mini-ITX home office build, we've actually hooked this exact system up to a Kill-a-Watt measurement device and provided the results in the step-by-step guide. And indeed, under all circumstances, it drew less than 65W at the wall, which accounting for power supply losses is actually just a 60W power draw.

So there's no question here - it definitely works. Even using standard power draw estimates per component (and the only components are the CPU, motherboard, RAM, and SSD), it could never be higher than about 80W, so I'm surprised PCPartPicker's algorithm put it above 90W.

As for Linux - yes, you can definitely load it up on this system, although you'll need to source the necessary drivers on your own. Installing off a thumb drive is no problem - that's how we got Windows 10 Preview on our test system.
« Last Edit: January 07, 2015, 07:08:26 AM by Ari Altman »

DCode

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Re: Total newbie asks about power supply
« Reply #2 on: May 13, 2015, 01:37:30 PM »
But how about the GPU option? For both cases recommended for this build our friends at pcpartpicker.com flag the following incompatibilities with the Radeon HD 7750 ...

  • 1 additional case full expansion slot is needed.
  • VisionTek Radeon HD 7750 1GB Video Card and Antec ISK 310-150 Mini ITX Desktop Case w/150W Power Supply are not compatible.

(I know you already answered but want to make double sure given the more aggressive needs of the optional GPU. Thanks.)

Ari Altman

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Re: Total newbie asks about power supply
« Reply #3 on: May 13, 2015, 01:57:09 PM »
But how about the GPU option? For both cases recommended for this build our friends at pcpartpicker.com flag the following incompatibilities with the Radeon HD 7750 ...

  • 1 additional case full expansion slot is needed.
  • VisionTek Radeon HD 7750 1GB Video Card and Antec ISK 310-150 Mini ITX Desktop Case w/150W Power Supply are not compatible.

(I know you already answered but want to make double sure given the more aggressive needs of the optional GPU. Thanks.)

PCPartPicker uses automated algorithms to find component incompatibilities. It's a nice start, but it's always a rough approximation, and is often pretty far off base.

The ISK 310-150 does indeed have a PCIe expansion slot, the only limitation of it is that it's half-height. Not a problem with the Visiontek HD 7750.

The 150W power supply in the ISK-150 will be plenty powerful to support the HD 7750 and a Pentium G3258 or even a Core i3-4160 processor.

A G3258-based system only requires 40W at full load at stock settings, according to my tests, which you can see here. Even overclocked it's under 70W, and a Core i3-4160 would be in between the two.

The HD 7750 cannot possibly pull more than 75W due to its design, which uses no PCIe power plugs, and in reality, draws under 50W. So in total, you'd be drawing less than 100W, well below the capacity of the power supply.

DCode

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Re: Total newbie asks about power supply
« Reply #4 on: May 13, 2015, 03:05:10 PM »
Thanks, Ari!

But the ISK-110 definately won't take that GPU, correct? AFAICT it has no PCIe expansion slot, half-height or otherwise (from Amazon link).

Ari Altman

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Re: Total newbie asks about power supply
« Reply #5 on: May 13, 2015, 04:24:36 PM »
Thanks, Ari!

But the ISK-110 definately won't take that GPU, correct? AFAICT it has no PCIe expansion slot, half-height or otherwise (from Amazon link).

That's for sure! The ISK 110-VESA cannot accommodate any expansion cards. Besides not not having space inside, it doesn't have a cutout in the rear panel, meaning a card cannot even be mounted, regardless of size.