It is "Akasa thermal adhesive  tape " with 0.9W/mK

there is no part number, just search for  0603 SMD resistors on ebay. You will get them  very cheap.
You cant change frequency while CGminer is running.

"....hash rate at only 1.5 Gh/s."

No, it is not he pool side, your miner  gets not enough power.

Ok, I measured  the current with 2.2K&10K configuration.
@ 0681 it is 0.7Amp!!
@ 0781 it is already 0.8Amp

I presume @0981 it is more then 1 Ampere pro miner.
No wonder  my hubs couldn't support more then 1.5 miners.

Update on my overclocking saga:)
With  BFGminer and  2.2K and 100 K combination i  got very good results:


This is Antminer @0A81 CONFIGURATION:   ZERO Hardware Error.
The cool thing is, that  my mining pool really  measured 2.3 GHS from my worker, so it is real deal:)


The problem is, that two completely different  USB3.0-HUBS could not support more then 1 Antminer, even though the could provide 4A. I am not sure why.
I will  wait for  my USB2.0 PSU powered  PCI card. That must provide enough power from my  600W PSU.

Tnx, after tweaking  with ports i  run all4 antminers  form BFGMINER @2GHS
I noticed that  Antimmer behave differently with  it. With bfginer the WORK LED only light up  when it sends result, while with CGMINER it blinking like crazy.
It is very interesting that i get almost ZERO HW!!
Now it is time  for  hardware hacking, again....

BTW
I overclock using "--set-device antminer:freq=0981" command

Thanks , will try it .
CGMINEr  just runs  not stable enough. Sometimes  he losts connection to miners, or work with high HW rate, sometimes  it goes perfect. depends on luck.

Can someone please explain how to use bfgminer with antminer?
I have the  nwools version, but it just dodnt find any device.
I deinstalled ZADIG drivers and only sintall the SILabs serial drivers

I cant get on btcguild website:(Errorcode: sec_error_ocsp_unknown_cert)

No  need for hotair station, just  fine soldering iron and skills

I also noticed  that i got less HW if I increase Difficulty.

Small R values will cause more current through the divider to the ground=> wasted current from your usb-port.

I really doubt you will manage to solder  through-hole resistors on the 0603 footprint

ok
New results from  overclocking attempts:

I upgraded my 4 Anminers with 10K and 2.5K  Resistors, and  connected only one antminer first.
Finaly i  managed to  get  very stable 2,4-2,5 GHS from one miner.
The overclocking procedure is not straight forward.

The antminer SilLab microcontroller seems to store some kind of calibration table  , which he uses to control PWM of the DC/DC converter and adjust the voltage for  TXO ( Frequency).
After you change the voltage output of the DC/DC converter those calibration values didn't match with reality, so you just cant start with high frequencies, the error is too high.
Instead start with  lowers  GHS possible: 1.4 GHS.
Wait until it stabilize, and increase the frequency by one value.
Step by step I managed to run Antimner at  0B81, which gave me about 2,5 GHS.

After i plugged the second  calibrated miner into USB3.0 HUB (4A max), the speed of the 1st miner  gone to 2.1 GHS, and the second  one gave 1.9 GHS.  The third miner just gone zombie...
Seems like there is not enough  power? But funny enough I got the same 2.5 GHS result from  USB2.0 PC port.... so current shouldn't be a problem here, probably....

I am, not quite sure WTF is wrong with AntimnerU1. Maybe some kind of connection/synchronisation errors with cgminer...
I tried to run  BFG miner, but it couldnt find any device at all....even after i deinstall zadig drivers.
Moreover CGMINER cant find a device directly from USB3.0 (my USB3.0 hub is connected to the USB2.0 Port) port.


I will purchase a PCI USB2.0 extension card with separate powersupply from the main PSU. Costs only 10 Euro, so i give it a try, in case there is not enough  current...

nah,  the hub is band new. I will  return it  on monday:)

BTW

I overclocked one of my 4 miners with 10K and 2.2K resistors.  and  noticed that not only that  Antminer performs better (stable at 2.2GHS) but  overall performance of  all miners is increased.

Is there any explanation for this?
Do all miners work independently form each other, or do they split the work like multicore CPU's?

you are right, i connected miners directly to my PC, and  everything goes ok.
But i doubt  my USB-ports have more power then USB3.0 Hub with 4A output. Most probably it  just sucks.

Dammit i get some kind of interference. When i run all 3 Sticks from same HUB one Miner tends to clok up and  producing mass of HW. If i run only 2, then the problem is not present.

I think the problem is with those  ZADIG drivers.

I tried to sue nwools bfg miner, but as i start the .exe  it just dont detect anything. I deinstalled the zadig drivers

BTW
Running at 2 GHS  at chip Temp.  just 40 C°  (room temp 21 C°)
Passive cooling FTW=)

Ok guys. I tried to overclock Antminer u1  according to  the official   guide.
I replaced  resistors  to 10K and 4.7K, to set the voltage near 1.2V ( I am sure the exact R Value is not necessary)
As  result I couldn't set any operating frequency  with  "nonce timeout" Error.

Then I replaced the R1 to 3.5K, that allowed me to  use  Antminer at 225 MHZ (all frequencies over it caused nonce timeout).
Instead  of getting 1.8 GHS I got  about 2.3 GHS but  too much  HW, so I lowered  R1 to  1.5K.
 That allowed me to run Antminer at max. 250MHZ, but getting  again about 2,3 GHS  with acceptable HW rate.Still  the miner got pretty hot, so i replaced the resistors back to the original state.
I also tried to vary   Timeout parameter   by setting it to higher values(from 20 to 100), that allowed me to start  Antminer at R1=3.5K R and 250MHZ, but still it acted VERY weird. The  "work" LED   was permanently "ON" and the miner delivered only hardware errors.


Can anyone explain my WTF? Who the hell posted this PDF with overclock instruction? What am i doing wrong?

PS
The test U1 was  powered through USB3.0 Hub  with max output current of 4A.

Hm,
 I also had one  faulty Antminer with high  HW Rate, it died today:(
It starts at 2 GHS as intended, but  after 2-3 min  it slows down to about 200 MHS. Most propably it is some  physical damage due to the  thermal expansion.
Lets see if my warranty will work in this case ( purchased on ebay)

How comes  you have so low HW rate?
  My ANTIMNERS are running at 2GHS @ diff 8. and i have about 150 HW to 1000 Accepted shares.
 What do i do wrong?
The  Antminers are  powered from SUB3:0 hub with 4 A output.
The hub is connected to the USB2.0 port on my PC, but i assume that  there is not so much data to transfer, so speed shouldn't be a problem.
 Miners are pretty well cooled to  about 35 C°
 What am i missing?

Did someone overclocked   Antminer to 4 GHS already?
I purchased big heatsink+resistors, and will try to overclock them  on Friday.
Will post my results here

 

So as far as I understand,  for clocking more then 2 GH/S  you need to replayce those resistors?
Because i  get  timeout erorr if i try to overclock to 2.2 GH/S.
I also presume you will need some better cooling. Maybe a big metal plate you can screw all Antminers to,  instead of this small   heat sink...hm...