Is this PSU going to cut it?

[2timer]

I need your opinions guys. I've specced an experimental uSFF build with the following components:

Intel G2120
Radeon 7850 stock clock
64GB SSD

Basically add a motherboard and that's it. This will be extremely lightweight. Now the question I have is about this power supply :

http://www.newegg.com/Product/Product.aspx?Item=N82E16817338045

It's got 2 +12v rails, and it's rated for 220W. According to my calculations that would just barely make the total wattage of the system which I figure to be about 225W.

This PSU has two +12v rails both @12.5A, so if the specs are to be believed, then at least there won't be a massive overflow of current through a single rail. I'm well aware that a 300W PSU would comfortably power this system, but what I'd like to know is if this PSU could do the job for almost half the price, saving me money.

And oh, I'm intending to play Bioshock Infinite on Ultra settings, so the CPU and GPU will be most certainly loaded. I imagine that the PSU will be straining as well, but the question is, will it hold up. Your thoughts are appreciated greatly.

 

[mfenn]

A 7850 is rated for 130W and a G2120 for 55W, combined that 185W. Those are the two biggest power users in the system, I would be astonished if the rest used another 35W. That being said, cutting it so close on a not-spectacular PSU doesn't sound like a particularly good idea to me.

 

[2timer]

Hmm, could you please tell me where you got the 130W rating from? My understanding was that a 7850, having a PCI-E connector, is rated for 75W draw at the PCI-E bus, and then another 75W at the connector?

 

[fralexandr]

the 75+75=150w is max theoretical draw for pci-e + 6-pin.
many cards run somewhere below their max theoretical draw.

furthermore, the 7850 is known for being highly overclockable, so under load, will not approach 150w when stock.
the 130w max load rating might come from legitreviews
http://www.legitreviews.com/article/1863/12/
or it might come from anandtech's review, assuming a ~10w idle (pretty typical idle for the last 1-2 gen of graphics cards)
http://www.anandtech.com/show/5625/...-7850-review-rounding-out-southern-islands/17

what case are you planning on using?
you might want to stick with a mini itx that uses a standard/full atx psu

the coolermaster elite 120 is currently $40
http://forums.anandtech.com/showthread.php?t=2320873
which would allow you to use a corsair cx or antec basiq whenever they're cheap

edit: also, if you're not already getting a 2GB 7850, you probably should, since bioshock infinite on ultra @1920x1080p uses >1GB (though at that resolution, you'll probably be averaging less than 60 fps)

 

[2timer]

I see, so the max theoretical draw is 150W, but real number is closer to 130W. Thanks!

If I were to use a standard case, my first choice would be the Sugo SG05/6. However, this will be a custom build, with the intent being a total volume of ~4L, and it will be necessary to build a case from scratch. So in fact, while a flex ATX PSU is not ideal, it will be necessary, and much cheaper than the alternative.

 

[Torn Mind]

If you click on the photo of the product, you can find more photos. One of them is has the label, and it says it can handle 18A on the one 12 V rail.

I can't find a review of the PSU you are looking at, but there are a couple for the 350 W version. Based on those tests, it will probably pull its labelled wattage.
http://www.hardwaresecrets.com/article/Athena-Power-AP-MFATX35-350-W-Power-Supply-Review/1282
http://www.kitguru.net/components/p...-350w-flexatx-power-supply-review-ap-mfatx35/

I would suggest undervolting your CPU.

You could get an i3 "T" chip, but that will cost quite a bit more than the Pentium and the clock speeds are lower by 300 Mhz.

 

[Termie]

The powertune limit of the HD7850 is 150W. See http://www.anandtech.com/show/5625/...-hd-7850-review-rounding-out-southern-islands

That makes sense given the 75W+75W maximum power delivery available. At stock clocks and stock powertune, you're looking at 80% of total TDP, or 120W.

Now, with a single 12V rail of 12.5A, you'll come pretty close to the limit of a single rail, although maybe others can say whether the PCIe slot power and molex connectors will draw from different rails.

My honest opinion is that you're spec'ing too powerful a GPU, both for the PSU and your CPU's capabilities. The most GPU I'd use with that setup is a GTX 650TI, which uses about 45W less power than the HD7850: http://www.anandtech.com/show/6359/the-nvidia-geforce-gtx-650-ti-review/

I'd also bet that it will be slightly bottlenecked by the G2120, but not nearly as much as an HD7850.

 

[2timer]

If you click on the photo of the product, you can find more photos. One of them is has the label, and it says it can handle 18A on the one 12 V rail.

I can't find a review of the PSU you are looking at, but there are a couple for the 350 W version. Based on those tests, it will probably pull its labelled wattage.
http://www.hardwaresecrets.com/article/Athena-Power-AP-MFATX35-350-W-Power-Supply-Review/1282
http://www.kitguru.net/components/p...-350w-flexatx-power-supply-review-ap-mfatx35/

I would suggest undervolting your CPU.

You could get an i3 "T" chip, but that will cost quite a bit more than the Pentium and the clock speeds are lower by 300 Mhz.

Undervolting is definitely going to happen. I'm planning on undervolting the CPU, GPU, even the RAM. Although realistically, I doubt a stable undervolt would save me more than 5W on the CPU? Still, I'll take it - every little bit counts.

 

[2timer]

The powertune limit of the HD7850 is 150W. See http://www.anandtech.com/show/5625/...-hd-7850-review-rounding-out-southern-islands

That makes sense given the 75W+75W maximum power delivery available. At stock clocks and stock powertune, you're looking at 80% of total TDP, or 120W.

Now, with a single 12V rail of 12.5A, you'll come pretty close to the limit of a single rail, although maybe others can say whether the PCIe slot power and molex connectors will draw from different rails.

My honest opinion is that you're spec'ing too powerful a GPU, both for the PSU and your CPU's capabilities. The most GPU I'd use with that setup is a GTX 650TI, which uses about 45W less power than the HD7850: http://www.anandtech.com/show/6359/the-nvidia-geforce-gtx-650-ti-review/

HOLY COW! Only 3 FPS less than the 7850 on B.I., and 45W less power? http://www.techspot.com/review/655-bioshock-infinite-performance/page3.html

Sign ME up! Those are numbers I like. I'm just wondering, how come I never heard about this? The prevalent opinion is AMD uses less power than Nvidia, blah blah blah. Is this really true?

Thank you man!

 

[Termie]

HOLY COW! Only 3 FPS less than the 7850 on B.I., and 45W less power? http://www.techspot.com/review/655-bioshock-infinite-performance/page3.html

Sign ME up! Those are numbers I like. I'm just wondering, how come I never heard about this? The prevalent opinion is AMD uses less power than Nvidia, blah blah blah. Is this really true?

Thank you man!

Well then, let me give you another reason to thank me: http://www.newegg.com/Product/Produc...82E16814162127

Use the coupon code on that page to bring the cost down to $89AR.

That's a great deal for that much processing power, and it's mighty small too, perfect for an SFF PC!

Now, just a word of caution - those Anandtech power numbers seem a bit unrealistic. Here are some other numbers that are probably more accurate: http://www.techpowerup.com/reviews/EVGA/GTX_650_Ti_SSC/25.html

Looks like about 20W less on average than the 7850. But that could help a lot with your system.

 

[2timer]

Well then, let me give you another reason to thank me: http://www.newegg.com/Product/Produc...82E16814162127

Use the coupon code on that page to bring the cost down to $89AR.

That's a great deal for that much processing power, and it's mighty small too, perfect for an SFF PC!

Now, just a word of caution - those Anandtech power numbers seem a bit unrealistic. Here are some other numbers that are probably more accurate: http://www.techpowerup.com/reviews/EVGA/GTX_650_Ti_SSC/25.html

Looks like about 20W less on average that the 7850. But that could help a lot with your system.

Aw man, you don't even want to know! Right now I could HUG you Termie! Even ~20W would be huge, when the margins are so slim. ~20W, for just 3 FPS on Bioshock? I will take it any day! The price too....

This is going to change everything... I think I love you man :wub:

 

[preslove]

Are you sure it has a pci-e slot op? It says "PCI-Express Connector No" in the details...

 

[2timer]

Are you sure it has a pci-e slot op? It says "PCI-Express Connector No" in the details...

It doesn't. Alot of power supplies don't ship from the factory with a PCI-E slot, simply because it's just another liability in the war to offer the lowest prices to the masses. But almost every graphics card ships with a PCI-E adapter. If there are 2 +12v rails, a PCI-E connector can be split safely between the two - assuming the PSU is over 400W. That's all playing it within the very "safe" side where manufacturers want.

I'm just trying to get some feedback on actual power usage and manufacturers ratings. I know a little about power supplies, but I'm not familiar with how far they can be pushed, other than better cooling allows higher performance.

 

[fralexandr]

fyi that 650 ti has 1GB vram.
Bioshock infinite at 1920x1080 ultra w/ ddof uses up to ~1.6GB, without DDOF ~1.3GB, so expect the 1GB version to to perform marginally worse than the 2GB version. You should probably not enable AA/DDOF
http://www.ocaholic.ch/modules/smartsection/item.php?itemid=991&page=1

also, if the devs haven't fixed bioshock infinite yet, you might have to play around with some out of game settings.
http://steamcommunity.com/app/8870/discussions/0/828934424216521384/#p3

 

[2timer]

fyi that 650 ti has 1GB vram.
Bioshock infinite at 1920x1080 ultra w/ ddof uses up to ~1.6GB, without DDOF ~1.3GB, so expect the 1GB version to be marginally slower than the 2GB version

After my initial excitement of "discovering" the 650 Ti, I soon wondered if I should get the 2GB or 1GB version. Thankfully, your post answered my question beautifully :thumbsup:

I'm looking at this card: http://www.newegg.com/Product/Product.aspx?Item=N82E16814500277

Other than the warranty, any reason to spend extra on EVGA?

 

[fralexandr]

zotac is fine, you might not be able to get as high of an overclock on it, but that's probably irrelevant for your current build

 

[2timer]

zotac is fine, you might not be able to get as high of an overclock on it, but that's probably irrelevant for your current build

Cool, that works for me :thumbsup:

 

[mfenn]

Now, just a word of caution - those Anandtech power numbers seem a bit unrealistic. Here are some other numbers that are probably more accurate: http://www.techpowerup.com/reviews/EVGA/GTX_650_Ti_SSC/25.html

Anandtech's power numbers are perfectly good, as are TPu's, they are just measuring different quantities. Anandtech measures total system power consumption (including PSU efficiency losses) whereas TPu measures card-level power consumption.

 

[mfenn]

Sign ME up! Those are numbers I like. I'm just wondering, how come I never heard about this? The prevalent opinion is AMD uses less power than Nvidia, blah blah blah. Is this really true?

Saying that "company X's products use more/less power than company Y's" is a uselessly broad generalization. The reality is far more nuanced than that because it depends on the individual chips used in the GPUs, of which both NVDIA and AMD make many variants.

Here's a chart, as you can see the two companies are well interspersed.

 

[energee]

I need your opinions guys. I've specced an experimental uSFF build with the following components:

Intel G2120
Radeon 7850 stock clock
64GB SSD

Basically add a motherboard and that's it. This will be extremely lightweight. Now the question I have is about this power supply :

http://www.newegg.com/Product/Produc...82E16817338045

It's got 2 +12v rails, and it's rated for 220W. According to my calculations that would just barely make the total wattage of the system which I figure to be about 225W.

This PSU has two +12v rails both @12.5A, so if the specs are to be believed, then at least there won't be a massive overflow of current through a single rail. I'm well aware that a 300W PSU would comfortably power this system, but what I'd like to know is if this PSU could do the job for almost half the price, saving me money.

And oh, I'm intending to play Bioshock Infinite on Ultra settings, so the CPU and GPU will be most certainly loaded. I imagine that the PSU will be straining as well, but the question is, will it hold up. Your thoughts are appreciated greatly.

You will regret it if you purchase that PSU. We can help you find a much better unit that won't set you back much more.

First, read the Newegg reviews on that Athena power model. Among the negative reviews: "This was originally advertised as having much higher output amperages. When I received the item in the mail, the label on the unit showed lower output amps. ..."

According to Athena Power's own spec sheet, the unit only actually only has a single 12v rail rated at 12A:
http://www.athenapower.us/products/power_supply/ap-mfatx22.html

It's a 220 watt low-priced unit. Just do the math.

What form factor/dimensions does the PS have to be?

 

[2timer]

You will regret it if you purchase that PSU. We can help you find a much better unit that won't set you back much more.

First, read the Newegg reviews on that Athena power model. Among the negative reviews: "This was originally advertised as having much higher output amperages. When I received the item in the mail, the label on the unit showed lower output amps. ..."

According to Athena Power's own spec sheet, the unit only actually only has a single 12v rail rated at 12A:
http://www.athenapower.us/products/power_supply/ap-mfatx22.html

It's a 220 watt low-priced unit. Just do the math.

What form factor/dimensions does the PS have to be?

Thanks. While it'd be reasonable to expect a single +12v rail on this size/price, surprisingly, I'm still seeing two, even on Athena's website:

+¹2v1: 12a
+12v2: 12a

Perhaps the Newegg review was referring to an erroneous amp rating?

 

[AnonymouseUser]

Get a 7790 and that PSU will be fine, and upgrade to an i3.

 

[mfenn]

Thanks. While it'd be reasonable to expect a single +12v rail on this size/price, surprisingly, I'm still seeing two, even on Athena's website:

+¹2v1: 12a
+12v2: 12a

Perhaps the Newegg review was referring to an erroneous amp rating?

Just because both rails are independently capable of 12A, doesn't mean that it can do a combined 24A across both.