Would you though? If it takes x amount of watts for a hot tub to maintain temperature of y with it losing heat to evaporation/convection then so long as you input x or less watts then your water temperature won't exceed the original design. Issues would arise when you add more than x amount of watts to the water in the hot tub. Then the temperature would rise until the increased delta t between the water and ambient air caused an equilibrium to be reached through evaporation/convection. This isn't an issue for a heatsink but it is an issue for a heatsink that humans would like to enjoy sitting in. In that case then it would make sense to run a water/air HX before the hot tub so that you add less than x watts and then supplement to reach x watts.

This could potentially work. I run a water loop for my 5970s and the water temperature is around 40-45 Celsius. A quick Google search puts hot tub temperatures in the 38-40 Celsius range. So, with a simple PID controller you could use GPUs for the bulk heating requirement for a hot tub and have a smaller heating element attached to the PID controller to maintain the water temp at the comfort range you want. The ideal solution would be a water/water heat exchanger so that your waterblocks aren't exposed to whatever chemicals/bacteria reside in your hot tub.

So, the 8 pin PCIe connector contains two additional ground pins. One of my rigs is a quad HD 5970 running on a Corsair AX1200 with a molex -> 6 pin PCIe adapter for the 8th PCIe plug. Pulls 1150w from the wall and no problems for ~1 month now. So long as your power is balanced across the available rails on the PSU AND you aren't exceeding the current draw limits of the PSU then mix and match adapters as you see fit.

I have no experience with 6 to 8 pin PCIe adapters but given how it is duplicating a set of ground pins I imagine whatever you find on Newegg/etc would suffice.

It all goes downhill from here  We need pictures for historical documentation so when you crest 5 GH/s we can point back and say "aww, look how cute it was!".

Payment sent for the pair of 5830s

I'd like to see something in the $5k range.  This way I can..

1) spread them out
2) if one goes down I don't lose all production
3) expand the farm more often

I pay around 0.11 USD/kwh after all the taxes and fees and such..

So if I understand, the numbers you give in the first post "7970: 515.4€" for 1 year paid in 6 month segments. At 0.18 USD/kwh it looks like it'll take you roughly 2 years to pay off the cards. Not bad I suppose if you already have the infrastructure and are able to keep those cards occupied by clients 100% of the time. When not rented by clients I suppose they could mine for your own account and you'll just have to hope that the price per bitcoin climbs out of this 5 USD/BTC plateau we seem to be at.

Will be interesting to see how your service turns out. I don't think I'll take advantage of it at this point as I think I have a way to get power at 0.07 to 0.08 USD/kwh which will make HD 5830s incredibly viable for myself.

In the end it is too expensive for most non-European users. Your very high power cost will require relatively high rates for this service for anyone outside of the EU. In the US by my calculations it costs me about $240 per HD 5830 for the card, the chassis to run it in(split across 5 cards) and then the power to run the card. I currently run out of my garage where I vent the waste heat(in winter months I had the cards in the basement to heat the house). I am looking at a small industrial warehouse with a pair of roof vent fans to run out of as my operation grows. This will drop my power costs as I'll be on an "industrial" plan instead of a residential plan so it further makes your operation cost ineffective to myself.

However! For Europeans who seem to have much higher power costs your service might be quite useful. The other case would be users who don't want to manage their farm as it grows. Unfortunately at this point though mining is mostly a hobby for some people and a serious investment for others. The first group enjoys running their farm, the second group saw this as a way to make money and would be turned off by losing possible profit.

Where in the Rockies? I'm out in Boulder myself. The biggest thing I'd be interest in is a place to co-lo my growing HD 5970s farm.. I'm a lowly apartment dweller and don't have the ability to feed any more juice to my farm. However, I might also be interested in a share of a crowdsourced FPGA farm.

Any idea on the size of chip and manufacturing process for the 45 for $45k you are mentioning? If each chip is $1k but is able to compete on a MH/$ compared to GPUs then it could be a viable option. I guess all I'm getting at is that I feel like this avenue hasn't been truly explored asides from cursory glances and the regurgitation of "common" knowledge.

Curious why, with a number of FPGA builders cropping up, there has been no mention of someone crowd sourcing funds for a run of ASICs on some of the cheaper processes.

A quick search pulled these guys up -> http://www.easic.com/low-cost-power-fpga-nre-asic-90nm-easic-nextreme/easic-nextreme-overview/

90nm is old tech which should translate to cheap and I would imagine we'd still see decent efficiency out of a chip.

There are a number of fabless manufacturers that sell portions of wafers that would let us avoid the immense outlay for an entire wafer and more importantly the masks.

This post of course has zero research behind it but with what I've seen on the FPGA threads there would be demand for a cheaper product that sat somewhere in the fpga range for power consumption and the GPU range for performance.

Thoughts? Anyone research this and find it unviable?

edit: I've seen a few threads with the same topic and everyone says "it costs a few million dollars for a run." easic's selling point is low costs per run. An article on their 45nm process quoted 20-100k for a run. Of course this is practically worthless without any information on the chip manufactured but keep in mind easic is making a business out of undercutting the bigger fabs.

Whew, there is a lot of FUD in this thread but it appears you at least have a solid plan. Mostly curious if you'll try to harvest the waste heat and how you'll go about doing it. I know you mentioned pre-heating your waterheater, going to stick around to see what you do. I myself built out a small farm of 8 watercooled 5970s. Hopefully you don't buy up all the DangerDen 5970 waterblocks!

Very interesting thread but I can actually chime in on this conversation about using a phase-change system to remove heat. If you're talking a traditional single-stage gas system like in your refrigerator then forget about it. The piping required plus the MINUSCULE load for each cold-head would make this cost prohibitive. Your best bet would be to repurpose a mini-fridge, use a proper condenser and throw a TXV for refrigerant metering and use something like r134a or n-butane/iso-butane and aim for evaporator temperatures in the 0-20 Celsius range. Then stick with your dinky little heatsinks and fans and not worry about having to mill expensive evaporators for such a small heatload.

Mini-fridges or even something like a deep-chest freezer would be the perfect insulated box to work with. The issue is such systems are designed to remove the heat from a load that doesn't generate additional heat. Without modification you will kill a freezer/fridge. That's where the replacement condenser and TXV come in to place. Make the compressor happy and you'll have shockingly low compressor loads and could very well run these FPGAs at astonishing speeds.

That all being said, compressed gasses are fun but can easily explode in your face with dire consequences if you aren't careful. Plenty of forums out there for amateur refrigeration. Take a gander at some of the things people have made and consider the tool costs. My own set of tools and gasses would buy a number of FPGAs and likely make me more money in the process

Would like to be whitelisted. Been mining for about a year now on 2 cards using GUIMiner on the desktop and poclmb on the linux 4 card miner. Looking to buy another 3-5 5970s to fill out all my PCIe slots.

Been mining with 8x HD 5830s at 900MHz and a pair of watercooled 5970s at 950MHz. Shopping around for more cards and this seems to be the clearing house.

I suppose even if they go about it inefficiently it still does help spread bitcoin through the technically savvy populous. Could be worse I suppose and have them go about attempting to disrupt the network.

Hanging out and such so I can buy up some more 5970s