My passion is to contribute to the Einstein@Home project which (amongst other things) is trying to prove the existence of gravitational waves - as predicted by Einstein nearly 100 years ago, but not yet directly measured. I've been doing this for more than 10 years and have no intention of quitting any time soon. After all, with advanced LIGO data soon to become available, things are bound to get interesting. Over that period, I've assembled a rather large 'crunching farm' that runs 24/7. Fortunately, I saved a lot during my working life so now, well into retirement, I can indulge my passion - well, at least pay the electricity bills.
To minimise costs, I reuse and repair stuff as much as possible. I'm not an electronics technician and I wouldn't really be able to diagnose or even properly understand circuitry. I worked in a University/training environment and did glean a little as part of managing training simulators. I've built/refurbished 100's of computers and am well aware how to diagnose simple problems like bulging caps on boards and in PSUs. I have a Weller soldering station and I've done maybe 15 or so successful repairs to motherboards/gpu cards. I've re-oiled fans (both CPU and PSU) but I've not felt comfortable enough with my skills to completely recap a PSU, particularly SFX PSUs where everything is so tightly crammed in.
I really got started with building a big farm when I bought 120 ex-business Optima brand PIII PCs (Tualatin Celeron 1300s) in a series of computer auctions for an average of less than $15 each. They were manufactured in 2001/2002 and I bought them in 2006. They had Delta DPS-175HB PSUs (SFX) with an (unused) ATX12v cable - 175W with approx 100W on the 12V rail. They also had Seagate ST320014A 20GB IDE drives. Very few of either of these components have failed to this day.
I ran these machines (and a variety of others) 'as is' until 2009/2010 when I retired them as part of a major upgrade. I decided to jump from PIII to Core2 Quad in one big leap, completely bypassing the whole P4 era. I actually did try a single Northwood P4 but decided I couldn't cope with how much power/heat and lack of output such a change would involve. I really loved my Tualatin PIIIs.
For the upgrade, I kept the case, HDD and optical drive and fitted a new board, CPU, RAM and PSU. I managed to find a supply of 300W SFX PSUs that were rated at 270W @12V. They were branded Ipex SS-300SFD but were made by SeaSonic and were listed as being 80+ although it doesn't claim that on the sticker. From measurements during use, I know the efficiency is quite good. I bought 60 for $13 each. They were superseded stock but were unused. They have been in 24/7 use for the last 6 years and now some are failing, because of bulging caps, I believe. I'm now weighing up whether to attempt repairs or to bite the bullet and replace them with something more suitable.
At the time of the 2009 upgrade, CPU crunching was king so multi-core was the way to go. Since then, GPU crunching is progressively taking over. My current fleet numbers around 90 machines (Linux x86_64) of which around 50 have suitable GPUs, mainly GTX650s and HD7850s. These were chosen to deliver the best output for the lowest cost (both capital cost and running cost). GPUs can be incredibly productive, so the push has been on to develop GPU apps for all sorts of scientific projects that were traditionally CPU only. When advanced LIGO data becomes available, it's likely there will (for the first time) be a GPU app to crunch it.
I'm sorry this became so long winded but I felt it would be useful to document how much of a nut case I am. If you're still reading, thanks for doing so. I decided to join this site because I'm seeking advice about re-capping PSUs and also understanding and diagnosing PSU behaviour. I'll create specific question(s) in the appropriate place for that. I've read quite a bit on this site and am impressed with the knowledge and skills of those who participate here. I particularly liked the PSU reviews. After having a long held belief that Shaw (MSY) PSUs are absolute rubbish, I was quite surprised to read the PSUSH80PGOLD850 review.
