Smallest possible PSU for a HTPC with a HD 5850

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Illex

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Nov 2, 2007
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I am currently planning a new HTPC with enough graphics horsepower to take it to the occasional LAN party. This is not my main gaming PC, but it will have a lot of "up-time" because my family will use it as media center, for this reason low power draw would be good.

Currently my planned specs are:

CPU: Intel Core i3 530
Mainboard: MSI P55M-GD45
Memory: Mushkin Stiletto 2x2GB, DDR3-1333
GPU: cheapest available HD 5850 at the time of the actual purchase
Hard Drive: Intel SSD 80GB + whatever old SATA drive I have around (I can probably recycle an old 500GB drive)
Disc Drive: LG CH08LS, BluRay ROM
Case: Silverstone SST-GD05B Grandia Desktop

Now all I need is the PSU to go with that to give me just enough juice to run this rig on full load, but keep the power draw to a minimum. I do not need any reserves for OCing or future updates.

From calculating the power draw on http://extreme.outervision.com/psucalculatorlite.jsp I get a little over 300W. So I was thinking about the Seasonic S12II-380 (SS-380GB) Bronze - 380 Watt PSU as a conservative choice. I am wondering if I can get away with using the even smaller 330 Watt version of the same PSU.

The PSUs above only have one 6pin PCIe power connector - I read somewhere that you can get around that by using an adapter on a different power connector, is that accurate?

Has anyone tried to build a setup similar to this and has some experience to share? Any input would be appreciated.

Cheers,
Illex
 
380watts will not cut it the 5850 needs at least a 400watt PSU. On neweggs PSU calculator they say a recommended PSU of at least 450watts for your setup but I would go for a 500watt.

Now the 5850 is a little overkill for a HTPC setup If you went to a 5670 or a 5770 you could get away with using a 400 watt PSU.
 
This is a good reliable power supply with all the connectors you need.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341016

Currently $40 after MIR so why not? With MIR I got the 600W a few months ago. Overkill for my system but cheaper than most of the power supplies that were the minimum I needed.

I assume of course that it is money you are worried about and not power draw from the wall. I am assuming you know that the computer will only draw as much power as it needs and that a power supply is most efficient when about 60% of the max load is being drawn from it.

A 5805 will draw a maximum of 170W off the +12V rails. When buying, you need to make sure that the power supply has at least 300W combined output on the +12V rails. You can find this out from the manufacturer. That's to be safe. You might be able to scrape by with 270W. Note this is the total draw on the +12V rails only.
 
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power_maximum-2.gif
 


+1 to that suggestion. Go for a slightly less powerful card but one that has better efficiency and requires less power. You don't need a top-end card to output in full 1080HD really so that card would still be overkill.
 
Hmmm.... a combination home theater pc and LAN parties. Interesting combination.

HTPC's do not require much in the way of a video card or power supply. The ATI Radeon HD 4770 would have been an appropriate choice. LAN parties are another matter.

Here are the official ATI Radeon™ HD5850 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

500 Watt or greater power supply with two 75 watt, 6-pin, PCI Express® power connectors.

The recommendation is for an entire pc system. That does not mean the power supply will always be drawing 500 watts. The pc will only draw as much power as the system requires. If you are in HTPC mode doing something that only requires the power supply to draw 100 watts from the wall outlet (mains), then that is all the psu will draw. It will not draw the full 500 watts. Power consumption for a typical gaming session averages somewhere around 300 watts or less for a system with one video card. That is just an average. However, there may be sudden power spikes of very brief duration during "intense" scenes in a game. It appears they occur when going from a near idle state to high power state. A power supply needs to be able to handle those sudden rapid surges in power.

I took a look at the specifications of the htpc case. It can accomodate an atx power supply up to 188mm (7.042 inches) in length which is very good.

Since the pc will be used primarily as a home theater pc I am going to make a recommendation that is overkill. HTPC systems should be as quiet as possible so I recommend the Seasonic X-650 Gold, 650 watt power supply which earned a gold certifcation for energy efficiency. It is silent during normal operation at lower loads which makes it ideal for home theater use. It's also more more than sufficient for LAN parties. In addition it is 100% modular so you only use the power cables you need. That would come in handy in a smaller pc case like yours. The unit comes with a 5 year warranty.

Here is a link to a very favorable technical review at Silent PC Review where the psu earned the Editor's Choice Award:

http://www.silentpcreview.com/Seasonic_X650

In addition here is a link to a competent technical review at jonnyguru.com. The psu earned perfect 10's for performance and functionality.

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=169

I just happen to have the X-650 in my newest system and can attest to it's silent operation at lower loads. The fan doesn't kick in unless the temperature climbs at high loads. It is a new design that combines passive and active cooling.
 
but then again a smaller power supply does not mean lower power consumption your psu could be 400 watts or 1500 watts if your pc needs 225 watts it wil get 225 watts from either one what you really need is a mid range(500-650) power supply that is very efficient between 30-50% capacity
 
5850 power requierement: 500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireXTM technology in dual mode).

Therefore, If you want the smallest one, this is my suggestion: ANTEC EARTHWATTS 500W.
This PSU has been made by SEASONIC. It's very quite, good price and gives you power enough.

 


That is not correct. You are speaking about the 500D . The 500 is from Seasonic .
 

Not that I don't think that the 380 couldn't handle it, but for $10 more you can get a 430 watt model , that has both of the required 6 pin connectors

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151074
 


The EA500 that you can get from Newegg or off the shelf at Staples ( If they haven't all been cleared out yet ) is the 500D, as I stated Delta took over manufacture of the Antec EA500 almost 2 years ago.
 
There are two different models:

ANTEC EARTHWATTS EA 500 - EC: It's from Seasonic and you can buy it (I have bought a new one six months ago... and it's from Seasonic)

http://www.hardwaresecrets.com/article/526

ANTEC EARTHWATTS EA 500D Green - EC. That one is from Delta.

http://www.antec.com/Believe_it/product.php?Family=MTE=

Those are the EARTHWATTS models from Delta:

380D, 430D, 500D, 650 and 750

Delta is manufacturing the CP (850/1000) and the SIGNATURE (650/850) series too.

The truepower (550, 650, 750) and the EARTHWATTS ( 380, 430 and 500) series are from SEASONIC.

FSP manufactures the QUATTRO (850/1000/1200) and the BASIC series.
 

the basic 550 is a delta
actually the true power's are from CWT
the true power trio are from seasonic
the quattro's are from enhance
 
If you are not going to OC, SilentPCreviews "Recommended List and a 9.0 at jonnyguru will do you just fine. I'd grab an EA-650 or EA-500

For comparison purposes , the list of 650 watters below contains performance ratings (10 scale) at jonnyguru.com / prices as per newegg on 02/26/2010 and ones w/ double asteris (**) made it onto silentpcreview.com's Editor's Choice List:

Note: Just because you see a brand name on this list, never make the assumption that their other lines are of matching quality. Silverstone for example has other models w/ 6.0 and 7.0 ratings.

Antec Signature 650W (10.0) OOS **
Seasonic X-650 650W (10.0) $160 **
Silverstone Olympia OP650 (10.0) NFS

Thermaltake Toughpower QFan 650W (9.5) NLA

Antec Earthwatts EA650 650W (9.0) $75

Antec True Power Trio 650W (7.5) NLA

XFX XPS 650W XXX Edition Power Supply (7.0) NFS

Antec NeoPower Blue 650W (6.5) NLA

BFG BFGR650PSU 650W (6.0) NLA

NorthQ Black Magic Flex 650W PSU (5.0) NFS

NFS - Not For Sale / NLA = No Longer Available / OOS - Out of Stock


 
Thank you for all the answers.

My aim is to keep the power draw low without compromising gaming power too much. Certainly one concern is to safe money, but also trying to be at least a little bit "green" 😉

I did read the minimum requirements from ATI, but in all the reviews of the 5850 I read the total system power draw was much less than that (300W or less). Adding to that, all reviews where done with much more power hungry CPUs than the one I intend on using.

Now I don't know about the power spikes mentioned by JohnnyLucky... does anyone have information on how much headroom in terms of power you would need to deal with this?

As to the rather smallish PSU I suggested: According to the "80 plus" specification the highest efficiency of the PSU is around 50% load. So I'm looking to use a PSU that fits this as close as possible for my system on low load (i.e. watching movies, internet surfing) - where it will spend to most time running!

The relatively few hours this system will spend on full system load should be possible, but are not the main point in picking the PSU. I am considering using a smaller GPU, but as I remain a gamer at heart that would be a painful 😉
 
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