After I published an article about Bios modification of ATI videocards on the example of Asus EAH4770 Formula a number of owners of these cards noticed the fact that my version of modified BIOS does not match all cards of this model. A short investigation revealed that there is another revision of Asus EAH4770 Formula. Owners of the second revision of cards mark out card′s inability to control fan speed meaning the fan is spinning at full speed regardless of card load or GPU temperatures. There is no slider for fan speed control in ATI Overdrive control panel. Other monitoring tools, for example, GPU-Z, show that fan is spinning at 30% of its maximum speed, but it reality it spins at full speed.
Further investigations of this issue ended with the conclusion that once again, Asus used the “right to make a slight modification of the PCB without any announcements” and began producing these cards with the new revision of the board and even didn′t change the its part number. These new revision cards have different power supply system which has some elements missing. The fan controller is not soldered therefore fan can′t be controlled.
After visiting Asus home page I figured out that there actually were photos of new board revision located on appropriate product page:
Lets examine soldering of elements by photo — all power supply elements are soldered.
And this is how the card looks in shops:
It is obvious that card′s power supply system doesn′t have one phase of GPU powering system soldered as well as some memory power elements aren′t soldered too.
Let try to find differences of these two revisions of Asus EAH4770 Formula videocards.
First (full) revision of Asus EAH4770:
As we see, the power supply system design of this revision of Asus EAH4770 Formula is totally different. There are four phases for GPU powering and two — for memory ships. Both revisions use same voltage regulator IC — uP6206:
For those who don′t know — voltage control using OS is impossible.
And here are differences in power supply system circuitry in particular:
In addition, the back side of the new revision has now fan controller soldered, while the first (full) revision has:
As a result of some elements being missing, new revision PCB can′t control fan speed.
Well, Asus is trying to save some money by simplifying the circuitry of videocard power supply system and removing fan controller IC. So let us be more attentive — we don′t need no scrap.