What is the heat like with the 47kohm SMD resistor? Does double the power = double the heat?
Speaking of HEAT...
I would like to address maybe a little overlooked so far details of the "overclocking quest":
THERMALS and COOLING...!
As a veteran "overclocker" (since the "glory" times of AMD/Intel 486-33 to 50/66 and Celerons) I believe that the proper cooling is very critical for successful overclocking. Looking at the current Gridseed cooling using so called "thermo pads" - full on the bottom, central for Gridseed chips only on the top, I was just wondering how a "quick and dirty" design decision this could be ?... Because it is BAD...so bad that fully deserve the term "
afroChinese engineering"...
Why...because there are so MANY air pockets between the chips (and other components to be cooled) and the Heatsink surfaces...mainly on the bottom...5 GOLDEN pads of the chips, with numerous vias, etc.. that there is NO WAY to make a full contact with the thermo pad first, and second - the heatsink on the other side...
Avalon/Gridseed saved time or money on a very simple thing...THERMAL PASTE (grease)...!?!
So yesterday I reach for my tube of thermal paste(TP):
1. Apply a small drop of TP on each of the 5 "golden" pads on the back...spread evenly to cover all visible surface of the pad(s) and fill the small holes (vias)...don't make it thick...just thin as possible is good enough...I used the flat tip of the small screwdriver...
2. Apply a small "X" on the central metal surface of the bottom heatsink...and again spread in a very thin but even layer of TP towards the edge of the circular heatsink surface ...
3. Reassembly carefully back...center properly...tightening the metal studs just good enough...I used the force
of my fingers...DON'T FORCE - you could damage the main board with tiny electrical traces inside...
4. Same procedures apply for the top part of the chips and heatsink...
The final effect of this "mod' is ...Gridseed chips are running at LEAST 15-20 degrees C cooler...
I am following this tread very carefully and experimenting with different mods myself for the last week or so...notice that my test chips are running "burning" hot when over 1000+ MHz...I can not keep my finger for more than 1-2 sec...which is probably like 65-70 C...So I installed a cooper RAM heatsinks to prevent from burning without the top heatsink during the tests...Still I could not keep my fingers any longer...
After the TP application they are just WARM to the touch...which probably about 45-50 C...
But the MAIN RESULT is - NO HARDWARE ERRORS for the last 24 hours run in the range of 1000-1025-1050MHz with 1.45-1.46V only for the Gridseeds...not even a single HW one...!
IMHO, I think that also could explain the "unstable" (I call them "slackers") chips in the same Gridseed device...performance differences, etc...
As usual...if you are not sure that you could follow these mods...don't do it...or do it at your own risk !
Many thanks for all the contributors of this tread ...and good luck !
ZiG
EDIT :
VERY IMPORTANT...!!!
The thermal paste HAS to be NON-CONDUCTIVE !!!...NO "Arctic Silver 5" or similar with metal (Aluminum) particles content...
ZiG