mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > Hardware

Reply
 
Thread Tools
Old 2016-07-31, 22:42   #155
Mark Rose
 
Mark Rose's Avatar
 
"/X\(‘-‘)/X\"
Jan 2013

29×101 Posts
Default

Quote:
Originally Posted by masser View Post
Given the power/space limitiations, what kind of GPUs could you add to these rigs?
That depends...

I had four boards stacked, but instead I have them lying on a shelf side by side now for better cooling. I could easily add graphics cards to all of them, but not on a single power supply.
Mark Rose is offline   Reply With Quote
Old 2016-08-01, 00:36   #156
Prime95
P90 years forever!
 
Prime95's Avatar
 
Aug 2002
Yeehaw, FL

162238 Posts
Default

Quote:
Originally Posted by masser View Post
Given the power/space limitiations, what kind of GPUs could you add to these rigs?
The whole point of my rig is to make the most cost efficient LL testing solution. GPUs of any kind would not fit my goal.

However, if you wanted to add cost efficient TF compute power then a GPU makes sense. I haven't done the research, but I don't think the picoPSUs could support a GPU -- it depends on how much power the GPU draws from the motherboard slot vs. power drawn from the separate 12V cables. If you'll do that research, then we might be able to figure out exactly what is possible.

After the power distribution is worked out, then you'd need to purchase an adequate power supply, find splitter cables for the 12V feeds to the GPU, make sure none of your 12V lines are overloaded, work out an optional enclosure with fans to push all that heat away.

Last fiddled with by Prime95 on 2016-08-01 at 00:38
Prime95 is offline   Reply With Quote
Old 2016-08-01, 02:43   #157
endless mike
 
endless mike's Avatar
 
Jan 2004
Milwaukee, WI

25×5 Posts
Default

Looking at my stack, (posted earlier in this thread) there's really not any room to stick a GPU into any of the boards. Not to mention heat issues that would arise. The CPUs are currently running in the mid 60 degree range, with both sides off the case.

Quote:
Originally Posted by masser View Post
Given the power/space limitiations, what kind of GPUs could you add to these rigs?
endless mike is offline   Reply With Quote
Old 2016-08-01, 15:45   #158
bgbeuning
 
Dec 2014

22·32·7 Posts
Default

The PCI spec allows a card to draw up to 75W from the motherboard PCI 16x connector.
(The only reason I know this is from the recent AMD RX 480 issue.)
The 6 wire ATX connector for a GPU is also limited to 75W but people routinely exceed that.

So given the i5-6500 and H110 uses 60W, we need a PicoPSU over 135W
assuming the ATX power for the GPU comes direct from the main PSU.
bgbeuning is offline   Reply With Quote
Old 2016-08-05, 04:05   #159
masser
 
masser's Avatar
 
Jul 2003
wear a mask

2·7·109 Posts
Default

Quote:
Originally Posted by Prime95 View Post
However, if you wanted to add cost efficient TF compute power then a GPU makes sense. I haven't done the research, but I don't think the picoPSUs could support a GPU -- it depends on how much power the GPU draws from the motherboard slot vs. power drawn from the separate 12V cables. If you'll do that research, then we might be able to figure out exactly what is possible.

I took a stab at this. I considered two problems:

1. Add cost-efficient GPUs to the 90W picoPSU systems you've built.

The most cost efficient purchase I could find with a TDP less than 52W (the upper bound would be very risky, I know) is:

GT 730, GhzD/D: 57.6, TDP: 25 W, Cost: $52.99

I recently purchased one of these for an energy efficient build; it only pulls 15 W (measured on a kill-a-watt) while running mfaktc. I used two metrics to make the cost efficient determination:

GVR3 = (3*GhzD/D)/(Cost+3*TDP) and

GVR4 = (4*GhzD/D)/(Cost+4*TDP).

2. What if George buys the 160W picoPSU for his next mobo/cpu/mem purchase, in order to keep the form factor, but increase the possibilities for the expansion slot on the mobo? Here I found two compelling purchases:

a. "Should be safe" Consider GPU with TDP <= 69 W. The most cost efficient purchase here that I could find:

GTX 750TI, GhzD/D: 139.7, TDP: 60W, Cost: $104.99

b. "Probably safe" Consider GPU with TDP <= 101 W. The most cost efficient purchase in this range:

GTX 950 (75W model), GhzD/D: 192.3, TDP: 75W, Cost: $144.95

Without more data, this is mostly idle speculation. It would be extremely useful to have actual wattage measurements for GPUs running mfaktc/mfakto. It would also be nice to know if anyone has tried to drive one of the listed GPUs with a picoPSU. I think the GT730 would be safe in George's current rig.

As for the cooling/noise issues, I will leave that as an exercise for the interested reader...
masser is offline   Reply With Quote
Old 2016-09-04, 18:59   #160
Prime95
P90 years forever!
 
Prime95's Avatar
 
Aug 2002
Yeehaw, FL

5·7·11·19 Posts
Default

Quote:
Originally Posted by endless mike View Post
Had my first issue between one and two days ago based on last check in date.
Attachment 14541
Note the melted white connector and wire insulation.
Attachment 14542

I just had the exact same problem

I thought it would be safe to run 3 boards off this one connector since different 12V lines from the PSU power each board.

Any recommendations on the best way to avoid this in the future? I have two CPUs out of commission until I fix this.
Prime95 is offline   Reply With Quote
Old 2016-09-04, 20:28   #161
endless mike
 
endless mike's Avatar
 
Jan 2004
Milwaukee, WI

25×5 Posts
Default

Quote:
Originally Posted by Prime95 View Post
I just had the exact same problem

I thought it would be safe to run 3 boards off this one connector since different 12V lines from the PSU power each board.

Any recommendations on the best way to avoid this in the future? I have two CPUs out of commission until I fix this.
I ended up rebuilding the connectors.
New PCIE ends from eBay (here)
14 gage solid core wire from the local hardware store instead of the 18 gage stranded core speaker wire.
Reused the barrel connector end from the original adapters.

I also only put two CPUs per adaptor instead of the three that they originally had. My PSU has enough PCI-E power connectors to make splitting them up possible.

I don't know that the heavier gage wire was absolutely necessary, or if just running only two CPUs per adaptor was all I really needed to do.

I rebuilt them in the second week of July, and they've been fine since (knock on wood).
endless mike is offline   Reply With Quote
Old 2016-09-05, 01:07   #162
bgbeuning
 
Dec 2014

22·32·7 Posts
Default melting

My system has 4 of those connectors.
It has been running 6 months without a problem.
One feels a little warm but the rest are cool.

The power wiring is taking up lots of space in my 4U case,
so I was thinking of redoing the wiring using

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

so you are giving me a second reason to redo the wiring.
bgbeuning is offline   Reply With Quote
Old 2016-12-22, 12:40   #163
cybergreg
 
Dec 2016

128 Posts
Default

I have read through the first 5 pages of this one, so don't know yet if anyone has suggested this, or even if it will work. A good friend of mine at Southampton University had this go viral a while back: https://www.southampton.ac.uk/~sjc/raspberrypi/ I have absolutely no idea whether you could run Prime95 on this or not or if you could whether it would be worth it or not. But I thought it looked cool
cybergreg is offline   Reply With Quote
Old 2016-12-22, 16:26   #164
Mark Rose
 
Mark Rose's Avatar
 
"/X\(‘-‘)/X\"
Jan 2013

29×101 Posts
Default

Quote:
Originally Posted by cybergreg View Post
I have read through the first 5 pages of this one, so don't know yet if anyone has suggested this, or even if it will work. A good friend of mine at Southampton University had this go viral a while back: https://www.southampton.ac.uk/~sjc/raspberrypi/ I have absolutely no idea whether you could run Prime95 on this or not or if you could whether it would be worth it or not. But I thought it looked cool
Raspberries are basically useless/terribly inefficient for what we do.
Mark Rose is offline   Reply With Quote
Old 2017-03-24, 15:32   #165
Mark Rose
 
Mark Rose's Avatar
 
"/X\(‘-‘)/X\"
Jan 2013

B7116 Posts
Default

Has anyone tried splitting the ATX power connector to more than 4 systems?

I'm only using ~320 watts on my 650 watt power supply and I'm tempted to squeeze another two systems in.

I'm using the EVGA GQ 650W (fantastic power supply, btw).
Mark Rose is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
A dream, will stay a dream ( new Nvidia Quadro) firejuggler GPU Computing 0 2018-03-28 16:02
@ George Gordon GMP-ECM 2 2017-09-04 04:05
Dream Build cappy95833 Hardware 10 2014-03-29 15:02
Dream PC plandon Hardware 39 2009-08-30 09:36
He had a dream fetofs Puzzles 8 2006-07-09 09:33

All times are UTC. The time now is 08:49.

Tue Jan 26 08:49:57 UTC 2021 up 54 days, 5:01, 0 users, load averages: 1.87, 1.82, 1.97

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.