ZTEX USB-FPGA Modules 1.15x and 1.15y: 215 and 860 MH/s FPGA Boards

[pazor]

try also this:




i use pad to contact the pcb to avoid to scratch and of course some grease.

the board runs 220MH/s@220MHz stable.

the second fan is necessary to transport the heat away.
the second heat sink can be smaller but i have only this at the moment. so i was taking this.

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[Turbor]

One of my older singles seems to be dead for no reason ..... It won't be recognized buy the mac (or any other PC i have in my household). It's listed as an unknown device under the Hardware Manager (Widows 7) and as i try to install the Ztex driver for this i always get the error: "There is no Driver ....blah blah blah".

I know this problem. Try to plug it in and out repeatedly. If that does not work, shut down the computer and disconnect all devices. Start the computer and reconnect the boards one by one. My advice is to not remove them once connected and running.

[BR0KK]

Tried that on two pcs.... Nothing helped so far. This unit seems to have died on me while i was playing arround with the Quad and the others.

[ummas]

Using pad`s and grasse is kind of strange... I`ll use my best pad for one chip today and i`ll see.

seccond think is, to put small heatsink on bottom of the board, small aprx. 75x75mm in the center of the chip.

and the last think is, to put water block on it... i got one to use...
those FPGA are real fun i must say.

[pazor]

Using pad`s and grasse is kind of strange... I`ll use my best pad for one chip today and i`ll see.

seccond think is, to put small heatsink on bottom of the board, small aprx. 75x75mm in the center of the chip.

and the last think is, to put water block on it... i got one to use...
those FPGA are real fun i must say.

 

[Turbor]

This unit seems to have died on me while i was playing arround with the Quad and the others.

I don't think so. I had this issue with both the 1.15x and 1.15d. It happened both times after removing and reconnecting them. I think the problem is on the micro USB side. Try there.

[roomservice]

This unit seems to have died on me while i was playing arround with the Quad and the others.

I don't think so. I had this issue with both the 1.15x and 1.15d. It happened both times after removing and reconnecting them. I think the problem is on the micro USB side. Try there.

Same issue here, after repowering und reconnecting the boards (usb and power) several time, it worked again.

[nelisky]

Using pad`s and grasse is kind of strange...

Look at the thermal conductivity and resistance numbers for whatever you are using. Using pads and grease is completely not useful unless you need to operate on a very much non flat surface and even there just grease will probably do a better job.

You see, good grease like MX-4 is rated at 8.5W/mK (higher is better), most greases I find in computer stores are at 1~3W/mK and most pads will fall at around 1W/mK. I have tried some high end thermal pads rated at around 6W/mK and some very good phobya ones at 7W/mK, but because the heatsink with the pushpins doesn't apply enough down force to compress the pads as designed, the result is that even 3W/mK grease works better than the best of pads.

I could use thicker pads but then thermal resistance comes into play and offsets any gain the pads could have on the grease. The pads (at least the very good ones) still have a place in testing scenarios as it is so much easier to snap on heatsink out and another in without having to clean up the grease mess left behind

So, in a nutshell, if you use grease+pad (+grease?) you will have the thermal conductivity of the worst link and the combined thermal resistance... not very useful.

[ummas]

I have got 7W/mK by Phobya, i`ll use.
Heatsinks are not good polished, lots of space in there. I`ll cut a square of phobya pad and screw heatsink on it.
As i said before, i got 0.5, 1.0 and 1.5mm - witch should i use ?

[Turbor]

I have got 7W/mK by Phobya, i`ll use.
Heatsinks are not good polished, lots of space in there. I`ll cut a square of phobya pad and screw heatsink on it.
As i said before, i got 0.5, 1.0 and 1.5mm - witch should i use ?

I'd start with 0.5...

[ummas]

donne:
1-stock on screws and sommekind of grease
2-stock on screws and Thermal pad 1mm 7kw (the 0.5 was 5kw only?)
3-stock and AS5 grease
4-stock and sommekind of grease

testing under unfamilliar conditions - 34*C ambient - stay tuned

after 15 minutes - this same....
i`ll take it for a trip sowmere cooler - 25*C ambient.
this same...1 208 and the rest 196.... board is almost cold

[Turbor]

  only this one board ?

[ummas]

i got water block witch fits perfectly, but i cant se sense in doing it :/

[Turbor]

i got water block witch fits perfectly, but i cant se sense in doing it :/

I had this one board (single) I was never able to cool down the way i wanted. I ended up taking a clamp (Schraubzwinge) to pull the heatsink down to the chip. The clamp is in place to this day. Perhaps you can take off one of the fans from one of the 196 MHz chips and try with a little clamp and some LIGHT pressure. This way you can see if it's a contact problem.

I checked my heatsink then and it was perfect level... you can check it on a window glass. Floatglass is very even.

[CA Coins]

This unit seems to have died on me while i was playing arround with the Quad and the others.

I don't think so. I had this issue with both the 1.15x and 1.15d. It happened both times after removing and reconnecting them. I think the problem is on the micro USB side. Try there.

Same issue here, after repowering und reconnecting the boards (usb and power) several time, it worked again.

Ditto.  I had this happened to me on 2 separate occasions, both on windows XP (on a laptop I use to program the fpgas individually).  The first time with the single it resolved after reconnecting several times.  The second time (with the quad) windows wouldn't recognize it even after several tries.  I plug it into the production machine running Ubuntu and it recognized it just fine.

[CA Coins]

Now a test to prove my theory.

I've applied some new AS5 and scrachted it linear very slightly. Then I've put the heatsink and moved it around a little bit. With the same result: the heatsink touches only at the corners. Here are the photos:




What can I do???

I am surprised that the contact is so poor even with the stock heatsink that should hold the heatsink down pretty good.  Do you know if the heatsink is bent or it is the FPGA?
 
The most straight forward way if it is the heatsink is just to replace the heatsink.  The alternative (which I know will sound like heresy to some) is to put quite a bit of the paste in the middle instead of the nice and thin layer that you have.  My first few boards I applied a thick layer of AR5.  Some of it will spill over onto the board.  2 of the boards I cleaned off the AR5 and re-applied a nice thin layer.  It actually didn't make a difference in the performance.  From measuring the temperatures with a probe, a thin layer and a thicker one didn't make any difference in the heatsink or the temperature under the LX150.  So what I am saying is that if you have an air pocket between the LX150 and the heatsink, you might be able to get away with putting a little bit more paste to fill the air pocket.  The thermal conductivity of AR5 is not as good as aluminum, but it should be good enough for running the LX150 (and definitely better than air). 

[CA Coins]

donne:
1-stock on screws and sommekind of grease
2-stock on screws and Thermal pad 1mm 7kw (the 0.5 was 5kw only?)
3-stock and AS5 grease
4-stock and sommekind of grease

testing under unfamilliar conditions - 34*C ambient - stay tuned

after 15 minutes - this same....
i`ll take it for a trip sowmere cooler - 25*C ambient.
this same...1 208 and the rest 196.... board is almost cold

Sorry for the multiple posts.  There seems to be multiple topics going on.

If you have a temperature probe, try measuring the temperature on the heatsink and directly under the LX150 to see if the heat is being conducted efficiently from the LX150 to your heatsink.  I had one board where the contact was not as good (no paste at the corners of the LX150).  The underbelly is hot while the heatsink was not as hot as the other boards.  Try to see if you get the same temps from the 4 LX150s.

For example, data I got testing a 1.15x, ambient 19C, bottom of LX150 = 30C, top of heatsink = 24C

[pazor]

Now a test to prove my theory.

I've applied some new AS5 and scrachted it linear very slightly. Then I've put the heatsink and moved it around a little bit. With the same result: the heatsink touches only at the corners. Here are the photos:




What can I do???

try to clean both surfaces with isopropylen alcohol. they became clean from the old grease.
you should be able to read the letters on the fpga chip.
after that put carefully a thin film of grease and the heatsink on the chip, fix it with the clips and start the miner.

good luck!

[BR0KK]

ill download ubuntu right now ...

But its not only limited to my mac. It doesn't show up in any windows PC i currently own....

[CA Coins]

That is weird that it doesn't work on any of the PCs.  Good luck with Ubuntu.  Hopefully it works for you.  Remember to use sudo before the command, ie sudo java -cp...