I'm thinking of buying 3 or 4 Antminer S3, but right now I'm puzzled about getting proper power supplies for these.
- Such EVGA 1300 G2 is quite pricey, are there any cheaper alternatives?
- Can 3 Antminer S3 be powered by a single EVGA 1300 G2 without problem?
- When overclocking 3 or 4 Antminer S3, how do you solve the power supply issue with 4 power connections each S3 (since a EVGA 1300 G2 only comes with 6 cables)?
I see that Biodom has already answered, but let me add my comments as well:
Alternatives to 1300G2: very few (like the Seasonic x1250), but I don't think you'll find less pricey PSUs in this class. The 1300G2 is a well-engineered supply; it is worth the money. I have many of them; really the only negative things I could say about 1300G2 are that it is relatively noisy (not as noisy as the miners, though) and that it is only Gold rated, not Platinum. You may want to consider buying 2 smaller PSUs (750W class) that may end up cheaper; each can run 2 S3's.
3 Antminers on a single 1300G2: yes, not problem. You can even overclock them a little.
If you want to use all 4 power connectors on an S3, you'll have to be creative. I have 8 1300G2's; they all came with 8 separate PCIe cables (6 6+2 pin, and 2 6-pin). I am in Canada, so what's in the box may vary from country to country. If you want to use all 4 power connectors on an S3 then you can only power 2 S3's from what's in the 1300G2 box, or find some quality PCIe splitters.
Splitters are generally fine as long as you keep the power below 200W-250W or so (a stock S3 would see about 175W per blade, or 350W total, so it should be ok to use 2 splitters to power the 4 power connectors); you just need to watch for heat buildup at the connection points (crimps points and friction locks mostly). Sometimes you get a cable with a poor crimp or some resistance on the mating contacts which can sometimes create enough heat to actually melt the cable housing and/or sleeving ... something you really don't want.
YMMV, of course, but I've never had the need to use all 4 power connections on an S3. I've played around with dozens of S3's, and all of them had the same overclocking limits, the same HW errors, and the same average hashrate whether I use 2 connectors or 4. I understand that others have had difference experiences.