$5k budget... being the cheapskate I am I would have a whole wall of bread boarded hardware with 5870/5970s. =) I suppose there is something to say for the savings the electricity in the long haul if you're doing 24/7 utilization, but I don't run my stuff often enough to make the investment in higher efficiency stuff pay off before it obsolete to something else.
If the rig makes you money then it makes sense to invest in the components that makes everything most efficient and you can just buy new and have it the next day. But it is more research approached its worth mentioning for around $500, about the price of 1 used GTX 980, I am doing 32 Gh/S (giga) MD5, about 2.5x as fast it... and that is two complete rigs... GPUs (6 total), PSU, mobo, cpu, memory, case and drive. And for another $60 - $70 it will be close to the equivalent of 4x 980 because I have 2 more free 1x pci-e slots left (1 per board) and enough PSU to drive one per GPU per rig. Granted, it is all used commodity hardware and I buy only when it being sold at a good price... except the PSUs, those are new (well refurb) 1050w GOLD 80 for $100. But used board/core duo cpu, 2gb ram, 500 gb drive... I had the same GPUs in a Xeon workstation with 2 full and 2 half pcie lanes, 16gb memory and there is no difference in the benchmarks, so the only the GPUs matter for the most part. Buying a high end CPU and stuffing it full of memory is a waste of money IMO unless you're doing CPU intensive hashes, but you wouldn't be bothering with all those GPUs if you were. The big difference, which can be a negative or a positive depending on how you look at it is to get that speed it is in two different rigs, not one. Often it is nice because I like to work on different jobs at the same time, and when not I can use a simple script to distribute the load.
Used market for either you're paying around $5 to $6 per GH with a 5870 and $37.5 per GH for a 980. Again, if you're running 24x7x365 and/or you're using this for commercial/profit and want to be able to keep scaling quickly then my budget minded approach does not apply very well.
Just food for thought for you or anyone else who turns up this thread that wants to know how to get good speed on the cheap. It's not hard... buy used older components (AMD for GPU) is all takes.
If the rig makes you money then it makes sense to invest in the components that makes everything most efficient and you can just buy new and have it the next day. But it is more research approached its worth mentioning for around $500, about the price of 1 used GTX 980, I am doing 32 Gh/S (giga) MD5, about 2.5x as fast it... and that is two complete rigs... GPUs (6 total), PSU, mobo, cpu, memory, case and drive. And for another $60 - $70 it will be close to the equivalent of 4x 980 because I have 2 more free 1x pci-e slots left (1 per board) and enough PSU to drive one per GPU per rig. Granted, it is all used commodity hardware and I buy only when it being sold at a good price... except the PSUs, those are new (well refurb) 1050w GOLD 80 for $100. But used board/core duo cpu, 2gb ram, 500 gb drive... I had the same GPUs in a Xeon workstation with 2 full and 2 half pcie lanes, 16gb memory and there is no difference in the benchmarks, so the only the GPUs matter for the most part. Buying a high end CPU and stuffing it full of memory is a waste of money IMO unless you're doing CPU intensive hashes, but you wouldn't be bothering with all those GPUs if you were. The big difference, which can be a negative or a positive depending on how you look at it is to get that speed it is in two different rigs, not one. Often it is nice because I like to work on different jobs at the same time, and when not I can use a simple script to distribute the load.
Used market for either you're paying around $5 to $6 per GH with a 5870 and $37.5 per GH for a 980. Again, if you're running 24x7x365 and/or you're using this for commercial/profit and want to be able to keep scaling quickly then my budget minded approach does not apply very well.
Just food for thought for you or anyone else who turns up this thread that wants to know how to get good speed on the cheap. It's not hard... buy used older components (AMD for GPU) is all takes.