820-2101-A replaced GPU, boot chime wont go pass apple logo

[protocold]

I have replaced defective GPU with a new one and machine boot up with chime but it wont go pass apple logo when the bar is around 50% it will just reboot.

I tried to boot linux and it wont go into anything with graphic but somehow pure text mode seems to be ok.

Where should I start looking?

 

[2informaticos]

Seems that machine fails when tries to load graphic driver.
Possibly bad chip, or solders...

 

[protocold]

maybe i killed the chip during the replacement... what's the max temperature that I should use on these GPU chips?

 

[2informaticos]

Temperatures differ for leaded and lead-free solder.
Also the rework stations are not equals.
Be aware, the temperature setting in station menu, is not the same as the value achived by motherboard.

I cannot give you a value for a particular station model.
You should practice in scrap boards, when configure your station.

 

[piernov]

Also be sure you got a good chip. Must have white underfill (not dark) and datecode > 0830 at least, model number G84-603-A2. Preferably "128-bit" memory bus, "64-bit" should still work if it's a good chip but it'll be limited to 128MB VRAM (it's probably a remarked G84-53-A2). Most chips on the market are remarked garbage (but the underfill color cannot lie on these GPUs at least).

 

[protocold]

Thanks piernov. Is it true that all G84-603-A2 have white underfill?

I have got supposedly new G84-603-A2 with white underfill and those chips are green, I presumably killed them as they turned brown after I put them on the board so I am really puzzled by the temperature.