Power Usage in New PC Build

barr08

macrumors 65816
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Aug 9, 2006
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Boston, MA
Hello everyone!

I am once again posting a PC question in the community discussion board, as there is really no other place on this forum to discuss PC stuff. /disclaimer

I am building a new PC, basically starting from scratch. The specs are in my sig. I have little experience inside a PC, but I am learning more every day.

I have a good quality Antec Earthwatts 500w PSU that I am planning on using. However, I am really worried that 500w won't be sufficient for my components. I would like to try, however, as I am doing my best to keep this build as cheap as possible.

I used this website to calculate the wattage I would need, and it quoted me at 440w. Am I cutting it too close with only 60w to spare?

Thanks in advance for your insights on this!

(Edit: Full component list added in post #5)
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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should be fine but if you plan on overclocking I would get something a bit bigger
Yes, my new MOBO has a lot of overclocking features, and I know people have OC'd the crap out of the i7 920. I plan on buying a new CPU cooler and PSU if/when I decide to OC.

For now, I just want to use my current PSU for a while, since I just dropped a bunch of dollars on the MOBO, Case and 2nd GFX card.

What kind of harm can an underpowered PSU do to your components? Would I just see sub-par performance, or can it fry my components?
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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I'd like to know more about the specifications. Otherwise the Earthwatts 500W is a solid power supply.
Components:
CoolerMaster Storm Scout Mid-Tower case
Intel Core i7 920 @ 2.66GHz (pulled from Dell Studio XPS)
ASRock x58 Extreme Motherboard
4x 1Gb 1066 DDR3 Ram (pulled from Dell Studio XPS)
1x 1Gb 1333 DDR3 Ram (Intel branded, bought in Marketplace)
2x Sapphire Radeon HD 4850 512Mb via Crossfire
Antec Earthwatts 500w PSU
1x 500Gb WD Caviar Blue HDD 7200RPM (pulled from Dell Studio XPS)
1x 500Gb Maxtor HDD 7200RPM (pulled from an External HD)
2x CoolerMaster 140mm Case Fans
1x CoolerMaster 120mm Case Fan
Stock Dell DVD/RW Optical Drive (pulled from Dell Studio XPS)
Stock Dell CPU Cooler (pulled from Dell Studio XPS)

Powered input devices:
1x eSATA 1TB WD External HD
1x Firewire 160Gb WD External HD
Logitech G15 Keyboard 2nd Gen
Logitech MX-518 Optical Mouse

Displays:
Dell 23" 1080p LCD via DVI
Vizio 42" 1080p LCD TV via HDMI to receiver (always plugged in but not always left on)
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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Boston, MA
That's an awkward amount of RAM given the triple channel interface.
This makes me uneasy as well. I had the 4Gb that came with the XPS, and I bought 2 more 1Gb sticks here on the marketplace (as is), and one didn't work. I figured the more, the merrier, even if I don't stick to the triple pairing (3Gb vs. 5Gb).

Unrelated to the power supply, could this odd RAM situation cause issues for me?
 

Eidorian

macrumors Penryn
Mar 23, 2005
29,081
287
Indianapolis
You'd get dual channel in pairs or triple with three. I don't think you're going to need triple channel or more than 4 GB of RAM but it's better to stick with the specifications.
 

No1451

macrumors 6502
Oct 20, 2008
474
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Ottawa, ON
Given the crossfire configuration I would really recommend a bit more juice. The overall wattage of your supply is NOT what you should be looking at, the key value to look for the amperage supplied on the 12v rail as it will see the highest draw(gpu, mobo, etc). There are some reviews out there that specify the wattage, most put it at somewhere between 22-25 amps.

Checking your rail outputs(if there are more than one) as if you happen to starve the GPUs your machine is going to crash.
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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Boston, MA
Given the crossfire configuration I would really recommend a bit more juice. The overall wattage of your supply is NOT what you should be looking at, the key value to look for the amperage supplied on the 12v rail as it will see the highest draw(gpu, mobo, etc). There are some reviews out there that specify the wattage, most put it at somewhere between 22-25 amps.

Checking your rail outputs(if there are more than one) as if you happen to starve the GPUs your machine is going to crash.
Ah yes, this sounds familiar. Could someone explain this a little further?

This is my PSU. From the specs -

Type - ATX12V v2.2
Output - +3.3V@25A,+5V@24A,+12V1@22A,+12V2@22A,-12V@0.8A, +5VSB@2.5A

I don't know if this is exactly what you are referring to. Is there a difference between general listed amperage and the amperage on the 12v rails?
 

TechieJustin

macrumors 6502
Nov 22, 2009
270
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Pennsylvania, USA
I say go with an even 500 watt. Remember you can reuse the PSU for your next build. I have a 550 laying around so when I build that linux machine I'll recycle it into that.
That little project is on my list of things to do... right under re-shingle the roof, build a shed, resurface parent's driveway, find & catch the animal running around in my attic...
Yeah, I'll never do it.
 

cherry su

macrumors 65816
Feb 28, 2008
1,217
1
Your power supply is rated as 80PLUS, which means that it is at least 80% efficient at any given moment. Therefore, it will supply at least 500*.8 = 400W at any given moment, which is a bit short of your quoted maximum (440W). A 600W power supply would be better.
 

Eidorian

macrumors Penryn
Mar 23, 2005
29,081
287
Indianapolis
Your power supply is rated as 80PLUS, which means that it is at least 80% efficient at any given moment. Therefore, it will supply at least 500*.8 = 400W at any given moment, which is a bit short of your quoted maximum (440W). A 600W power supply would be better.
At 100% peak load it would take 625W AC to crank out 500W DC from the power supply. (That's where the 80PLUS and other certifications come into play.)

On average you don't want to load a power supply over 80% constant. 400W constant from a 500W power supply is safe. This just reinforces my advice to go for at least 600W.
 

No1451

macrumors 6502
Oct 20, 2008
474
0
Ottawa, ON
Ah yes, this sounds familiar. Could someone explain this a little further?

This is my PSU. From the specs -

Type - ATX12V v2.2
Output - +3.3V@25A,+5V@24A,+12V1@22A,+12V2@22A,-12V@0.8A, +5VSB@2.5A

I don't know if this is exactly what you are referring to. Is there a difference between general listed amperage and the amperage on the 12v rails?
Based on this you have roughly enough to power both video cards(assuming full load and accuracy of those numbers), however the 12v rail powers a LOT of things, theres still the ~130watt draw of the CPU(again, worst case 100% scenario).

Normally a 500 would be sufficient, however the Earthwatt line is NOT known to be a good line.

Corsair, Seasonic, Thermaltake Toughpower, Silverstones are generally pretty good. I'd recommend 650+
 

Eidorian

macrumors Penryn
Mar 23, 2005
29,081
287
Indianapolis
Based on this you have roughly enough to power both video cards(assuming full load and accuracy of those numbers), however the 12v rail powers a LOT of things, theres still the ~130watt draw of the CPU(again, worst case 100% scenario).
Where did you get the 130W power draw for the Core i7 920?

Normally a 500 would be sufficient, however the Earthwatt line is NOT known to be a good line.
Where did you hear this from?
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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Boston, MA
You may also check here to see if your PWS is listed as certified for your graphic card and eventually see which models are:

http://ati.amd.com/online/certifiedpsu/index.html

Here you can find the requirements:

http://www1.sapphiretech.com/us/products/products_overview.php?gpid=244
Unfortunately, the only supported Antec Earthwatt PSU is the 650 for my card. Thanks for these links, though. These are very valuable.

Normally a 500 would be sufficient, however the Earthwatt line is NOT known to be a good line.
This is not what I hear. The wattage is a bit outdated, but the PSU line is widely accepted to be a solid one.

However, after reading everyone's opinions, I do think I need a better PSU for this rig.

Would there be any harm in using my current PSU until the new one arrives? I want nothing more than to use this bad boy right now!
 

No1451

macrumors 6502
Oct 20, 2008
474
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Ottawa, ON
Where did you get the 130W power draw for the Core i7 920?

Where did you hear this from?

The first is based on specs from Intel(check their spec sheet), the second based on looking at some numbers for a quality 500watt power supply and examining the power delivered by the 12v rail. The Earthwatts SUCKS, look at the amperage ratings, too much in the 5v and not enough where it matters. The Antec TruePower line however is pretty good, it's more focused on the enthusiast sector which is what this machine is going to be.

@barr08: not **** as in low quality or unreliable, they are **** because they have low 12v rail values, you need to take my words in the context they matter: in relation to THIS build. If you were building a lower-specced machine I'd say throw it in and call it a day, but you aren't doing that so set it aside and get something that can actually fit your needs.
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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Boston, MA
What do I need to keep in mind when buying a new PSU? As in what does it have to be compatible with? Is it just the processor? I see a lot of them say right in the name if it's compatible with the i7. Is that the only thing I need to look for?
 

Eidorian

macrumors Penryn
Mar 23, 2005
29,081
287
Indianapolis
The first is based on specs from Intel(check their spec sheet),
TDP isn't power drawn.

the second based on looking at some numbers for a quality 500watt power supply and examining the power delivered by the 12v rail. The Earthwatts SUCKS, look at the amperage ratings, too much in the 5v and not enough where it matters. The Antec TruePower line however is pretty good, it's more focused on the enthusiast sector which is what this machine is going to be.
Does this reflect the quality and reliability of the Earthwatts line?

What do I need to keep in mind when buying a new PSU? As in what does it have to be compatible with? Is it just the processor? I see a lot of them say right in the name if it's compatible with the i7. Is that the only thing I need to look for?
I'm going to give a vote to a Corsair 650W power supply.
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
1,362
0
Boston, MA

No1451

macrumors 6502
Oct 20, 2008
474
0
Ottawa, ON
TDP isn't power drawn.

Does this reflect the quality and reliability of the Earthwatts line?

I'm going to give a vote to a Corsair 650W power supply.
1) No it isn't but it's usually a good estimation of what you can expect a chip to draw.

2) No it doesn't but we only need to take it in context of the discussion at hand, anything else is entirely irrelevant to his needs

3) Corsair makes some solid supplies(750 model in my machine, never had a problem yet), however they can be sort of pricey, especially the HX series.
 

Eidorian

macrumors Penryn
Mar 23, 2005
29,081
287
Indianapolis
Corsair seems like the fan favorite from what I read on Newegg and Amazon. I was really trying to keep the cost on this low, but I have these components, and I'd like to keep them running (haha), so this seems like a pretty solid investment.

Any opinions on these? -
Antec Earthwatts 650 - $80
Corsair 650 - $80 after MIR
Corsair 750 - $100
Antec Earthwatts 750 - $85 after MIR
There's always OCZ.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817341017

http://www.newegg.com/Product/Product.aspx?Item=N82E16817341010

1) No it isn't but it's usually a good estimation of what you can expect a chip to draw.

2) No it doesn't but we only need to take it in context of the discussion at hand, anything else is entirely irrelevant to his needs

3) Corsair makes some solid supplies(750 model in my machine, never had a problem yet), however they can be sort of pricey, especially the HX series.
Thank you for elaborating on your views.
 

barr08

macrumors 65816
Original poster
Aug 9, 2006
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Boston, MA
OCZ specializes in RAM, right? Are their PSUs solid?

Also, would it make more sense to just bite the bullet and get a higher wattage PSU? Does the 100 watt difference justify the $75 extra dollars, or do I just go for the gold? I'm feeling like maybe spending the bit extra will be good in the long run. Maybe next time I upgrade, I won't run into this issue.
 

No1451

macrumors 6502
Oct 20, 2008
474
0
Ottawa, ON
Sorry if I didn't make myself clear, my statements are all based on absolute worst case scenario, and I have/do use an Earthwatts in my little server machine, the build quality is good, though not as good as my old Seasonic.

OCZ gets something of a bad rap, but I used my ModXtreme for 2 years without a fault. Of those you noted barr, I would select the Corsair if it was for myself, their customer service is usually fairly top notch(had a batch of bad ram from them)

OCZ specializes in RAM, right? Are their PSUs solid?

Also, would it make more sense to just bite the bullet and get a higher wattage PSU? Does the 100 watt difference justify the $75 extra dollars, or do I just go for the gold? I'm feeling like maybe spending the bit extra will be good in the long run. Maybe next time I upgrade, I won't run into this issue.
To the best of my knowledge they do the same as a lot of these companies and have their PSUs made by someone else, a lot of these parts are rebadged pieces of kit. I have no experience with OCZ's newer PSUs but my old 780watt served me very faithfully until my sad WCing leak:(.

A few extra dollars spent now usually saves more later in case you choose to upgrade. Chances are that if you upgrade in the next 1.5years your PSU(if you got a good one) will still be up to the task.