Hah! I'm kinda worried about that with 1/5 your usage

I told her, 'i really want to see what happens when the meter rolls past 99999'

34752 and counting..

There's absolutely no way those cards require 600W.

If they do, you might as well just forget about them entirely, with that kind of power draw you're going to be spending more in electricty than you'll make in bitcoins.

I stand by my 375W maximum per card estimate.  Someone can drop the cash and feel free to prove me wrong

Either 4x 450W PSUs or 2 >800W PSUs, but 2400W is crazy talk.  You want padding, not a padded room.

I <3 the interwebs.

http://www.amazon.com/Dremel-220-01-Rotary-Tool-Station/dp/B00068P48O/ref=sr_1_1?ie=UTF8&qid=1312923977&sr=8-1

I can't find specifics for this card, but I think that holds pretty much true at stock voltages.

A single-gpu 6870 has a TDP of ~150W, so logically this dual-gpu would TDP at ~300W.

In reality, it's probably slightly less than that due to sharing the same PCB. However, you'd easily make up for that in overclocks, which would pretty much be a requirement on these cards.

I'd give yourself room for at least 350W / card, perhaps 375W if you plan to ramp up the voltage.

For 4 of these, you'd need at least 1500W at that top end, not accounting for the rest of the system (~70-90W on average), and this would put you near or past the maximum for that silverstone 1500W PSU linked above.

I'd recommend a dual-PSU setup with a pair of >=800W units.

That makes the total cost for such a system..  $_$

Anyone have an appx TDP on this bad boy outside of "requires 600W PSU"?

Guessing ~300W max?

There is only one important advantage that keeps all my money in banks.

FDIC insurance.

If someone at the bank fucks up, it gets robbed, burns down, etc, I keep all my money.

Networked banks (chains) even more so, since no single bank actually has my specific stack of money.  Unless all the banks in the chain burn down my money is relatively safe.*

* this probably isn't entirely true - a failure of the bank's database + backups could potentially wipe out my stack of money.  Your home is probably considerably less immune to fires, etc.

Don't have an exact bill to read, but back-of-the-napkin estimates:

1,692kWh for ~ $292 / mo @ $0.174/kWh

Most of the hot air from my rigs is vented outside so the AC cost isn't huge.

[edit] that's just my rigs, I usually have ~$100 on top of that for normal household use.

The moment debtors, mortgage companies, utilities and supermarkets accept bitcoin, we'll be there.  Until then the need to 'pay the bills' in $<local fiat currency> will dominate.

Correlation generally doesn't equal causation, but in this case I think both the drop and the spike were wholly intentional.  Someone testing the waters to see if the market would react in a predictable way, and I think it certainly has.

A wise investor with enough money to move the market like this will be looking for a saturation point.  I expect to see quite a few more wild swings while this person/group plays around, until the market grows large enough to make high-volume, low-margin transactions more predictable and reliable.

l. o. l.

I think churning money out of this tiny, unregulated market is why they're here.

Unless the OS locks up

That's not an error.  Those are the normal messages aticonfig spits out when you have it reconfigure your X server. 

It's telling you that the current xorg.conf isn't initialized (also happens with -f to force),  that it's using the previous xorg.conf as it's base, and that it's saving you a backup of the previous config to xorg.conf.original-0. 

If it failed to create a new xorg.conf for some reason, it would tell you that instead.

Assuming it's not the same '4th card' that isn't working among all three machines, it's probably a BIOS config issue.  You may have to reduce port speeds for the 16x slots when all four slots are occupied, for example.

I did a quick search and didn't find anything relating to the motherboard not being able to utilize all 4 PCIe slots, but it's common for board to disable a 1x slot when both 16x slots are occupied, to provide greater bandwidth to the second 16x.

I'm not sure what you're reading, but everything that I've seen shows crossfire hurts performance.  Miners using crossfire are either leaving value on the table, or they're also using their rigs for gaming where crossfire is worthwhile.

Your cards will hash faster isolated.

It looks like there's plenty of room between them.  The PSUs can handle quite a lot of heat as well, I think they'll be nice and happy there.

The real truth is we're all lining the pockets of the exchange owners.

The miners are the ones making this all possible in the long term, and deserve what little pocket lining there is to get.

Neither is anyone expecting an instant shift to ASIC mining on a large scale.  No startup is going to be able to offer cost-effective ASIC chips right out the door.

A $2000 ASIC rig that performs 1/4 as well as a $2000 GPU rig is only worthwhile in the very-long-term due to energy savings.  It's like spending $40,000 on solar panels to 'save money'.

<clairvoyancehat>
I think it will be at least 6 months before you can buy an ASIC miner at all, and it'll be a year minimum before they're cost effective
</clairvoyancehat>

Your GPUs are safe for now.

Addendum to the above since I didn't actually answer your question - I have 4x XFX 1GB 6950s (ZDDC model @ 830mhz with two fans).  I can push them to about 355MH/s.

In linux, I cannot downclock the memory more than 125mhz less than the GPU clock, I can't overclock any of them past 885mhz without issues, and I can't alter the voltages to try to stabilize them past that.  Not that I would want to - they run hot, and suck down near 200W each on stock voltages.

I can safely say I won't be getting more 6950s unless there are not other reasonable options.  Without the 58XX series cards in the mix, however, they're pretty much it if you want a semi-reasonable $ / MH ratio.

+1 - if your miners are unstable, you've got some other problems.  You'd be better served working out those bugs than working around them.

Tell us more about your OS and hardware, any overclocks you're doing, etc. Perhaps we can help spot the problem.

Do not buy a 6950 relying on being able to unlock the shaders.  This has been beaten to death over and over on other threads here and several other OC forums.  

There is no 100% guarantee you'll be able to unlock shaders on any particular card, even two cards in the same production run may act differently, and the odds of getting one that actually will unlock seem to be dropping quickly.

Avoid the 1GB models if you want to have a chance; none of these are reference cards, and from my personal experience and reading accounts of others, it's highly unlikely you'll unlock shaders on these models.

The 2GB cards have better luck, if you find a reference 2GB 6950 it's your best chance to unlock shaders.  However, newer revisions of several of the 2GB cards appear to be hard-locked (physical disconnect of extra shaders).

Read through the reviews for a particular card to get an idea if it seems to be unlockable.   Also assume that you'll be voiding your warranty right out of the box, not every company is as lax as XFX