what minimum PSU would you recommend to run 2x6990's?

[Dimsum]

Just wondering what power supply wattage those of you running 2 6990s are using? Will a 850w suffice or must i get the 1200w one?

[1715213931]

1715213931

[Xephan]

Just wondering what power supply wattage those of you running 2 6990s are using? Will a 850w suffice or must i get the 1200w one?

Estimated about 400W per 6990 without overclocking so 850W is barely enough and certainly not safe for long term at full load. 1KW is probably the least you need for safe long term usage. Or you could buy two 600W that should be cheaper than a single 1200W

[Dimsum]

Damn! 400W when not even being pushed? ok ok .. will have to get the 1200W one then! Unfortunately the case I am building this in wont have space for 2 PSUs, so looks like it will be a single 1200W PSU! Thanks for the help!

[grue]

Damn! 400W when not even being pushed? ok ok .. will have to get the 1200W one then! Unfortunately the case I am building this in wont have space for 2 PSUs, so looks like it will be a single 1200W PSU! Thanks for the help!

go caseless (also has better cooling)

[Dimsum]

go caseless (also has better cooling)

I wish I could, but I don't have much space in my room, so I need a vertical tower to house it in. At the moment I have the side panel off on the current case and my future case can have both side panels off (even though the motherboard tray will block most of one side) - so its the best I can do but it should be fine. The nights get pretty cold and I keep my window wide open which also happens to be by the PC case so it balances out.

[Xephan]

go caseless (also has better cooling)

I wish I could, but I don't have much space in my room, so I need a vertical tower to house it in. At the moment I have the side panel off on the current case and my future case can have both side panels off (even though the motherboard tray will block most of one side) - so its the best I can do but it should be fine. The nights get pretty cold and I keep my window wide open which also happens to be by the PC case so it balances out.

You could always put the second PSU on top of the case or something
It'd be cheaper to run on a pair of PSU loaded under 70% than a single big one loaded up at 90%. The higher the average load, the faster the PSU will die and therefore cost you more per bitcoin due to the replacement cost. Also PSU tend to be most efficient at around 50% load so you'll save another few % off your electrical costs.

[Dimsum]

You could always put the second PSU on top of the case or something
It'd be cheaper to run on a pair of PSU loaded under 70% than a single big one loaded up at 90%. The higher the average load, the faster the PSU will die and therefore cost you more per bitcoin due to the replacement cost. Also PSU tend to be most efficient at around 50% load so you'll save another few % off your electrical costs.

I am really short on space - even the top of my case is taken - joystick, lamp, external HDs lol Besides, i'll only be maxing out the GPUs when I sleep. As I work from home, this is also my work PC and I mine whilst working but at a setting that doesn't tax the GPU's. I don't pay the electricity bills so its not such an issue for me.

I wish I had the space to leave this all caseless and out in the open!

[Bobnova]

Get a good quality 1200 unit (Antec and Corsair both make excellent ones, I'd get the Corsair AX1200 personally), they'll easily run a pair of OC'd 6990s plus cpu/etc.  Pretty good efficiency while they do it, too.

[ctoon6]

also running a psu over 60-80% will make it loose efficiency.

it may be worth the investment to go 80 plus http://en.wikipedia.org/wiki/80_PLUS, the power saved may pay for itself over the lifetime of the product.

[Dimsum]

Funny you both mention those because I was consider a Corsair TX 850W V2 or the 1200w PSU - Both of which are 80plus Bronze Certified!