Quote from: christhegoth on September 01, 2014, 10:46:29 AM

Continuing the Pencil-modding an S1 thread we have...

Playing with Server PSU's!

Pencil-modding thread is here:

http://necellularsites.net/go-Cj9hgoUnpTc/undervolt-bitmaintech-antminer-s1-pencil-mod-technique-bitcoin-mining.html

By pencil-modding you change the power factor from 0.42 GH/w to about 0.5 GH/w. But...

If you use a server PSU as well it takes the s1 to about 0.55-0.6 GH/w. Which is handy stuff. And if you want it even better marry it up with an s3 ( non-overclocked ).

I've got this rig now running. I have a pencil-modded s1 and a non-overclocked s3 running on a 750w server PSU ( not crappy ATX's/Desktop supplies ). It's a Dell Poweredge 750w.

- I get 370w for 440GH on the s3 ( used to be 440w running 2 ATX's to power it ). That's 1.18 GH /w.

- I get 205w for 110GH on the s1. That's 0.54 GH/w.

Average it across the 2 units ( using 110GH slices of hash ) and you have:

4 slices of 1.18 GH/w
1 slice of 0.54 GH/w

Do the math. If you combine it you get 550GH at 575w. Which is 0.96 GH/w. Which is the same factor as my Coincraft Desk at Turbo M mode ( overclocked ).

So that's another 3 months out of your s1 you can squeeze before you have to switch it off? It'll be something like that.

Handy eh?

Server PSU's require soldering to fit cables you can then connection block to, and you need to trick it into thinking it's on. This site does the tricking bit:

http://www.rcgroups.com/forums/showthread.php?t=1292514

I use uk 1.5mm flat cable, as it's rated at 20A when exposed to air. The Dell unit I have has 3 rails doing 20a each. So 2 rails go to the s3 ( one per side ), and 1 rail covers the s1 ( 1 going to both sides ).

Et voila. A bit more hash out of your unit.

And if you turn down your s3 to 175 freq you can get the power factor up to 1.55 GH/w for the s3 whilst still pumping out 340 GH from it. It's a pretty flexible rig. Which is handy with BTC price low at present.

Enjoy

I've added a couple of pikatures of the arse-end of the PSU ( Dell Power-edge 750w ) to show you what you need to do. There is soldering involved.

http://gothfiles.org.uk/images/ServerSelfie1.JPG

http://gothfiles.org.uk/images/ServerSelfie2.JPG

With those cables in place all 3 rails can be tapped for 20a each at 12v. The cables are 1.5mm twin & earth cores ( UK ).

The grey cable links the 3 pins that are needed to trick the PSU into turning on. This was made out of a ribbon cable for a floppy drive. Hacksaw off bits of connector to make a block of 3x2 and a block of 2x2. Remove all the metal bits ( teeth ) bar the ones needed to access the 3 pins. Push the blocks you've made onto the pins. They'll fit snugly. 3x2 at the left in this case ( with 2 teeth left as there are 2 pins to access ), and 2x2 on the right ( with one tooth left for that one pin ).

Then link them ( the 3 teeth you've kept ) with a bit of ribbon cable, by pushing the cable between the teeth ( which breaks the insulation and makes the connection to the cable ).

You should only have 3 teeth total across the 2 blocks if you've done it right. Plug in a kettle lead and she'll fire up.