Power Supply Advice

I'm going to be in need of a new PSU soon and its for a 3 card set up, each will be about as power full as a HD 5850, I have a Phenom II 720 C2 revision, I was wondering what I would need in a PSU for my system and what makes a good PSU a good PSU like rails and amps and such?

some of my choices so far



I love antec but that rosewill has good reviews and a lot of people bought it.

I have the 850w rosewill bronze, I've never had a problem with it, and I've had it almost a year. Only gripe i have is the cables that come with it are really short, makes cable managment difficult.

The Antec has more amps and is a better brand, so I'd go for that between those two.

Antec of out personal preference. I've used one for 4 years now, never failed me at anything : ]

I have the Antec Quattro 850w

so more amps is good? what about rails?

Single rail psu's are preferable just because you don't have to pay attention to what wires you're plugging into which video cards. If you have multiple 12 volt rails, just make sure that each video card has its own rail to depend on. To do this you just have to look at the cables in order to see what rail they are using. Use the cables from one rail for one graphics card, then use the cables from the second rail for another graphics card, and so on.

I'm not entirely sure about it, but I think more amps on a rail means more power is going through it, so for graphics cards that demand a lot of power, you're going to want to make sure that there is enough amperage on the rail that you're connecting your graphics card to. From what I've seen, I'm pretty sure 100 amps is enough for four of even the most demanding cards, meaning each card would get 25 amps.

how would you tell what rail it is on, and if it is modular like that antec one? or would each one have its own rail?

You will probably need a psu with a rating higher than 900W. I am assuming you will be using this build for bitcoin(why else would you want 3 5850's coupled with a 720 lol), so you want to get one with a really high efficiency rating. (calculate if the added efficiency will pay off, compare cost of lost power due to efficiency to price) Personally I would go for a non modular design, because the extra plug will also add resistance to the circuit, again reducing you efficiency. This loss of efficieny is probably very small, but if a non modular design is cheaper than a modular one, i would go for the non-modular one(unless you are one of those guys who likes to spend hours and hours on making their case look like the god-damned Archimedes death ray). those 5850 babies peak at around 200 watts a piece, and I [url=http://www.lostcircuits.com/mambo//index.php?option=com_content&task=view&id=54&Itemid=42&limit=1&limitstart=5][u][b]this [/b][/u][/url] chart says that the max power consumption of your cpu is around 56 watts, but i would take 75 watts just to be safe. Add all the cooling, hard drives, motherboard, etc. etc. and you will need something of at least 850 watts. [url=http://www.hardwaresecrets.com/article/Understanding-the-80-Plus-Certification/742]This[/url] website however suggests psu's are most efficient when they supply around 50% of their max rated wattage. However, on the [url=http://www.hardwaresecrets.com/article/Understanding-the-80-Plus-Certification/742/3][u][b]third page[/b][/u][/url] of that article, they explain the different efficiency ratings(80 plus, 80 plus bronze, 80 plus silver etc.). Again, compare that efficiency rating to the extra dwollas you gotta hand over to them. It's all about the money. I am of course assuming that bitcoin will draw 100% load, if this is for bitcoin at all. You probably will want to do some calculations befor buying anything, because the price difference is quite big between psu's. For instance, if we compare the "[url=http://www.newegg.com/Product/Product.aspx?Item=N82E16817182072][u][b]bare minimum[/b][/u][/url]"(850w)to the "[url=http://www.newegg.com/Product/Product.aspx?Item=N82E16817171055][u][b]top of the line[/b][/u][/url]" in efficiency we are suddenly faced with a $140 price difference. It might be your best bet to buy something in the middle, but again, make some calculations. I made a little [url=http://www.megaupload.com/?d=5PIMK80Z][u][b]spreadsheet [/b][/u][/url]to help you on your way with the calculations.

I don't have office installed yet but going from what I've been told this would be a good one for 3 5850s max load, yes its for bitcoin


it seems the best for the price to me, I've used raidmax in a build before, something was in the way of a fan and it was making a noise but I fixed that, seems to be a common problem but if thats all thats wrong with it then thats okay

GigaBuster.exe said:

how would you tell what rail it is on, and if it is modular like that antec one? or would each one have its own rail?

It's usually marked somewhere on the psu or the cables. If not then it should be in the manual at least. Most modular psu's (that I've seen anyway) mark it on the PSU where you would plug the modular leads into.


If you look at the pictures of the Antec PSU, you can see that the plugs for the modular leads are all labeled according to which rail they are on.

I have a Rosewill Extreme 850watt running two 5770's in crossfire never had a problem wonderful PSU and the price is RIGHT!!

What i like about the Xtreme is the intake fan is in the front of the PSU so it gets cold air from the front fan and blows it out the back!!

Also i had a Antec 1200watt and had to RMA it twice when i got it back from the RMA the third time i just sold it on EBAY!!


129.00 Newegg

have a look through this website,


the reviews for power supplies and the insight you can pick up from this website are second to none

i suggest you download openoffice and look at the spredsheet i made, because it will show you the money you will save by buying a more expensive psu. It took me a while to make, and you will see that buying a $240 power supply instead of a $100 power supply will save you money, not to mention the longer life expectancy & better warranties. Just god-damn look at it lol.

^ Buying expensive power supplies secures you a PSU for your next two to three builds if you take care of it. It's the same thing as having a large engine in a light pick-up truck thus improving fuel economy due to the fact the engine has to work less. In a simple "Computer to car analogy" done right.

Yup, the 2 last posts sums it up

why get the raidmax, when you can get the pc power and cooling 950 for the same price?

one other thing with PSU's

dont look at the over all wattage.... look at the wattage on the 12v rail.

most power supplies will have 95% of their power on the 12v anyway, but some try to advertise 1000 watts, when only 800 watts are on the 12v. in effect... this means your buying an 900 watt psu for the price of a 1000 watt one. (as most components like the cpu, mb, any 4 pin molex, and gpu all pull off the 12v)


here is antoher link if you still don't have openoffice or excel. It is a google online service. Good luck!(By the way, spend some time getting your cable managment right, it is absolutely essential to allow as much ventilation as possible. Three of those 5850 cards so close to each other creates a lot of heat you need to transfer. Also keep in mind you will have a small heater in the room you will be putting the system in, so if you keep it in your room, ventilation might not be your best option)