This is total bullshit. Bitcoin is a worldwide distributed effort, there are at best estimate 20-30,000 miners/cards floating about mining right now. The United States alone is made up of about 20-30million gamers. Dropping 20,000 second hand gpus across the nation is not going to be some huge glut that gums up the workings of the entire second hand market.

It's weird how misinformation seems to catch fire so much more easily than real information. That's why the OP hears "oh 6990s! awesome for mining!" when they are in fact one of the worst mining investments.

5970s are far superior to 6990s for bitcoin mining, though their resale value will be likely a bit lower.

Give a man a fish, he eats for a day, teach a man to fish...

http://bitcoincharts.com/bitcoin/

I swear every day I use these forums I wish for multiquote.

Basically what these folks have been saying though. One of the great advantages of mining over buying coins is you can re-sell your hardware if things go south so you have less sunk cost than a buyer. When you submerge hardware in oil you've basically destroyed it. You will basically never be able to get the oil out fully, and except for someone else who wants to use oil to cool, no one will buy that. And the mineral oil still requires cooling. There is no magical free cooling method, heat needs to go somewhere regardless of the cooling method. Don't forget that oil has some not so great properties to it too, like high viscosity for poor mixing. A machine running full blast 24/7 with many hot videocards will create incredibly hot spots that will not necessarily transfer to the entire reservoir without mixing.

So you need to 1) Mix oil 2) Remove heat from oil 3) never expect to get rid of your hardware once submerged.

@OP which 5830 do you have? I probably should have asked that earlier. Not all 5830s have voltage control just FYI. They require a programmable VGA Voltage regulators.

EDIT: Quoted wrong guy, ah well.

Source for allowable range of voltages?

Anyway, every chip is different, some have higher tolerance and are limited by heat, some have low tolerance for voltage even when heat is not a factor. I believe it has to do with power leakage, though I can't say for sure as I'm not a CompEngi.

Just use MSI afterburner. Done and done. Use dummy pluggys and not crossifre too.

I agree, but with reservation. Don't forget there can be huge variances. Look at deepbit, they have 2250Gigahash/second[/u] and they still hit block times of 2.5 hours. In theory with 281 times less processing power you could see 281 times as long to break a block (or in other words a month+). Soloing is something more people should do, but it bears the unfortunate downside of potentially being a very painful thing to wait and watch.

There is a demand for bitcoins, for both legal and illegal purposes. The legal purposes are useful, the illegal ones... we'll see.

5850s being out of stock have nothing to do with anything really.

For a mining rig it doesn't really matter. You're going to be running the PSU and GPUs 100% (probably OC'd) 24/7. Your main concern is a power supply that has sufficient amperage, and is rated to put out continuous power at high temps in the range that you need it. The cards are going to be getting f'd up anyway, a small amount of ripple really makes little difference to these set ups.

I mean, obviously the best quality is better, but a pass means that the PSU is solid enough to do its job, and that's what you need for a mining rig.

Based on... what exactly?

So many misconceptions about power:

Those reviews are calculating Total system power draw from the wall. Not the draw of the card from the PSU.

Well this is big money, probably the mafia running this.

You dont mine for them, someone knocks on your door.

Don't buy 5830s for $150, that's a bad bad deal. You'd be better off buying 6870s for around that price. 5830s are only sought after because they retail for ~$100.

I'm glad to see someone not looking to immediately buy 1000Watts+ for no reason. First things first, "xxx watt" is not the only factor. There are plenty of "850 Watt" power supplies out there that will almost 100% for sure die a gruesome death running 4x 5830s.

I would recommend an 850Watt PSU not because it's necessary, but because unless you know enough about power trimming, it might become necessary. Get something simple like a http://www.newegg.com/Product/Product.aspx?Item=N82E16817139022 and you will be golden. It's pretty cheap for what you get. You can get cheaper but you'll need to do research.

Terrible advice has been bolded. Do not invest thousands of dollars into GPUs until you do a lot more research about what bitcoin is, how it works, and how mining works. In fact, I don't recommend investing thousands of dollars unless you have thousands of spare dollars lying around.

There was some good advice in the quote though. CPU mining is totally worthless. Don't even bother. If you have a decent video card you can mine on that using one of the many clients found on these good forums. Again do some research though, this isn't a magical money fountain, you will still need to do some work on your own.

There was a site that used to give you .5 BTC to get you started. I can't remember the name though and they're probably dead now that BTC is $18. Can anyone remember? faucet or something?

EDIT: I see the OP mentioned it already. Sowwy OP.

Probably 6870s. They're plentiful, they go on sale a lot, they hash a little worse than a 5850 and use less power. They're not as efficient for your dollar, but such is life. If you can find one on sale for $150 - $160 it's not a bad deal. They do about 300MHash last I heard, which is about 1.875Mhash/$. Not great, not awful (for comparison 5830s do about 2.75 MHash/$, and 6990s do about 1.14Mhash/$)

Well, I've been arguing that the simple growth model is wrong for some time now. I was merely pointing out that the advice "its more profitable to buy than mine because..." is often touted but is only correct under certain circumstances. Freakin's graph is awesome and helpful.

I don't know that it will necessarily hold true though in the future, so buyer beware.

That's not true. That's only true if the number of coins you can mine are less than the number of coins you can buy for the same amount of money. At 30% difficulty increases mining rewards you much more greatly than buying. At 60% difficulty increases however buying rewards you more greatly. Assuming static increases of course.

If for example however difficulty precedes price you might lose out (that is to say if you buy mining hardware right before a large difficulty jump that precedes a corresponding price jump it could be different profitability)

Pretty simple really, 5xxx series cards are all last gen. They stopped being produced/bought/stocked half a year (or more) ago. Look online for 6xxx gen cards, they are a little more expensive, don't hash quite as well, but they're still very good hashing cards, they are not out of stock anywhere. The reason is that this is what is being bought up and stocked by retailers, not older generation technology. The market is pushed by gamers, and gamers don't want old stuff, they want new stuff. We managed to scrape up the dregs of what was left over and unwanted.

There is a fairly large used card market, and thats where you'll find some older gen cards, though people are snapping those up now admittedly. But check ebay as an example, there are still > 100 5870s for sale on any given day. At bloated prices, but they're there.