Glad I could be of some assistance.

A Bronze-rated PSU at 50% load achieves 85% efficiency, which is about the same as a Silver or Gold at or near 100% load. The difference is, the Bronze costs less and will probably last longer if ran conservatively. Mining places a continuous load (as in "24/7") on the power supply and graphics cards, which is not the same as "average computer use". So having an adequate power supply is a must, and a little overkill is recommended.

Also if you're running at only 50%-70% load, you don't have to worry about whether the PSU is single-rail or multi-rail so much, as you won't be putting stress on it. You don't have to buy a Gold-rated power supply to be efficient. They are nice though.

I'd like to add Enermax to that list. I've had one for years and it's rock solid.

It's not overly surprising that a cheaper power supply popped after running at full load continuously for 2 hours. You can see by looking at this link of 80 PLUS ratings that 50% of rated load gives you optimal efficiency.

http://en.wikipedia.org/wiki/80_PLUS#Efficiency_level_certifications

Running a power supply beyond 80-85% of it's max rating continuously is inviting trouble. Here's what I would do. Add up the power consumed by your GPU cards and CPU, then round up a bit to account for the motherboard, RAM and fans. Then add 2 zeros onto the end of that figure and divide by 50, 60, 70, 80, whichever percentage of efficiency you'd like to achieve with your power supply. That will tell you how many watts you need.

Here's a chart I downloaded from somewhere that shows how much power the various GPU cards require, in addition to megahash rates, etc...

http://i93.photobucket.com/albums/l59/lytlesnake/VhgVh.gif

I think the (80 PLUS/Bronze/Silver/Gold) power supplies are great if you want to spend the money. But remember, you can also apply the 50% Max Efficiency rule to cheaper power supplies, which is probably ideal if you're trying to build an overall cost effective miner. By overall cost effective, I mean striking a balance between initial cost and electrical efficiency. Then again, probably a majority of modular PSU on the market have an 80 PLUS rating at this point anyway.

Well, the cheap Powercolor 4650 card in my PC topped out at a whopping 27.1 Mh/s. That's with Windows 7 set for best performance, and the GPU and RAM at max in ATI Catalyst. Then I turned it down so the card doesn't fry.

Despite my incredibly low hashing speed, I've got 39 shares on BTC Guild. So at least that's working.

Now that I've figured out basic mining... might as well build a rig with some real cards. Until it becomes a financial loss to pay for the electricity, screw the calculators! This is fun.

Agreed. If I were going to build a rig solely for mining, I'd get a cheap motherboard and used cards, put it in a milk crate, etc... The $1,000 rig was using a much nicer mobo, SSD and high end power supply. That way I'm getting the components I wanted for my next build instead of just a mining rig.

My computer is on 24/7 much of the time. If I put another card in this one, I'll probably have to upgrade the power supply though. And if I'm gonna buy a new power supply, I might as well just start building a new rig.

I think I'm past the point where I want to invest $1,000 or more into a mining rig. However, I've been planning to build a new PC for a while anyway, and mining could help offset the cost of a few components in the short term. The computer I'm on now could use an upgrade from this Radeon 4600 series card too. It scores pretty low on the Windows Experience Index.

So I'm still looking at some cards, but it's probably a good thing I was broke this week. Otherwise I may have spent unwisely.

For anyone looking to get in cheap without trolling endlessly for 5830 and 5850, here's a half decent deal on XFX 5770 for $110 at Tiger Direct. Ends today.

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=5316156&CatId=3669

I did just possibly find a nice deal on a 5970 though... 

I have relatives in Canada. Then again, they'd probably just keep the money. 

Amazon has free shipping too. I heard it can take several weeks before they ship though, which in the mining world, is an eternity. So don't buy these. 

I just woke up in the middle of the night to tell you that. Carry on.

Well, I ended up being outbid on that card anyway. It's up over $190 now. That's pretty high for a used 5850. Didn't get any of those Sapphires on sale either. I did the responsible thing and paid bills first. I was still gonna get 2 after all the bill paying, but then I refreshed my browser and the sale was over. I'm gonna call them in 10 days when I have more money and ask for that same deal if I buy 3 or 4 cards. Worth a try anyway. Looks like they still have plenty in stock.

Sale's over. 

To run 1,300 watts at 80% efficiency you'd need a 1625 watt power supply. I suppose you might find one somewhere, but it's bound to be expensive. I would go with (2) good 850's or higher.

5850 cards average 171 watts, so that's 1026W continuous just for the GPU. Add in 40 watts for CPU, some for RAM and cooling, etc... I think that's pushing a 1,200 watt supply too hard. I wouldn't doubt that it can be done though.

If I were going with a single supply and (6) cards I'd probably get the 1,500 watt Silverstone supply then. That should do nicely. Or you can get an adapter cable from cablesaurus that joins two power supplies on 1 mobo. OK, sorry I keep editing.

OK, thanks for refreshing me on how ebay works guys.  I thought the bidding history showed the true highest bid, etc...

About to pull the trigger on 3 of those brand new Sapphire Xtremes at the weekly special price before it ends.

Right, I understand that part of the bidding. I was just assuming that people look at the bidding history first, so they don't bother to bid lower than the highest bid.

I know, that's exactly what I was looking at. I'll try and retract my bid on that auction so I can get at least 3 of those Xtremes today.

[edit] This ebay seller is being really cool so far. Doesn't look like it will be a problem to cancel my bid. I didn't mean to bid on an auction that started out with a high reserve if it already had a bidder. That way the price doesn't keep getting driven up on these cards. I must not have refreshed my browser before bidding, as the first bid is showing up only about 1/2 hour before mine.[end edit]

I seem to remember the asterisks, but it's been a while since I've actually bid on anything. Thanks for the reminder. Duh!

See, I need to put together a mining rig to sharpen my mind. It's been getting rusty apparently.

Well, either ebay was hacked, or I confused that auction with one for a 5870 where I know for sure I was the first bidder. I guess that's what happened. I'll probably just do the decent thing, honor my bid and buy the card. $178 for a reference 5850 isn't the worst deal in the world, but those Sapphyre xtremes are on special today. I'll still have to get some of those too. 

Well, maybe I'm going crazy then. I could swear I was the first bidder on this card by many hours, and then someone else placed a bid, but I'm still the high bidder. But according to the bidding history, I'm the second bidder.

F@ck it, I'm gonna have to turn the computer off and get some fresh air then. Either ebay is acting up, has been hacked, or my memory is frighteningly bad and I'm also slightly paranoid.

Why else would someone place a lower bid after you've already bid? It locks you into a higher price than the reserve. I'm seeing users with variants of m**_*, b_*** bidding on multiple auctions like this. I don't live and breathe ebay every day, so I could be wrong, but it looks suspicious.

The one I linked to a few posts up supports Quad CrossFireX, so it looks like a pretty sweet mining board at $105.

BTW, I realize you don't use CrossFire for mining. I'm just pointing out that it supports a lot of cards for the money.

I might go with this ASRock here. http://www.newegg.com/Product/Product.aspx?Item=N82E16813157262

It's $40 more (after rebate) than that Biostar, but it has more slots, and they appear to have better spacing too. You could run 4 or 5 cards on this mobo with an adapter/extender or two.

To run 3 cards on the Biostar you'll need an adapter, and I think a good one is about $15. So that puts the 2 boards only about $25 apart. A lot of people do use that Biostar though, so it's a proven board for mining.

Greetings tech geeks and BTC prospectors! My name is Jason. I just got hip to bitcoin this week, after seeing the cable news story about the cafe that accepts BTC. I'm not a gamer, but I do like building computers. It looks like I've been bitten by the bug.

I plan to start out with a modest rig of (3-4) 5850. $6 to $10 per day profit doesn't seem like a lot, but even at the low end that's upwards of $150/month that I could spend on things like shoes and socks, sandwiches, etc...

So unless I get outbid on every video card I try to buy, I'll be posting pics of my first rig in the near future. Happy mining!