Sapphire Radeon HD3870 fan problem

[Dato Marmarashvili]

hi all, I won 3 GPUs on ebay.com sapphire HD 3870.
i have :
cpu: core 2 duo E2180 2.00GHZ = TDP 65 W
RAM: 3GB 800MHZ
motherboard : ABIT-45CV
PSU : REXPOWER 450W 12v=20a

on that computer #1 card works perfect, fan spins as it must.
but other #2 and #3 card fans does not spin, but when temperature goes up to 75-80 celsius fan starts spin at 24%, i tried Evga Precission fan control and discovered that fans work but when i turn off Evga Precission, fans stop spinning...

I tried on enother computer ( i have 3 of them, third ones psu is too weak 320w)

CPU: core 2 duo E8400 3.00 GHZ = TDP 65 W
motherboard: Dell optiplex 755 sff
Ram: 3GB 800MHZ
psu: Rexpower 400W 12v=19a

On That one GPU #1 and #2 fans does not work, but i can control them via evga precission.
but GPU #3 fan works as must...
All Of Thous Cards Are In perfect working condition, using Evga Precission fan control i launched furmark and got standard score for 3870... they are fully working but, sometimes on some PCs their fan does not spin, I fully deleted and reinstalled Drivers, also Reinstalled windows, but it did not help. EVERYTHING IS OK EXCEPT FANs, please help someone,i don't have any idea what's going on...... and sorry for bad english....

 

[Dato Marmarashvili]

it was wrong bios on booth cards, i reinstalled it on oem, and it works as new. write here if have questions ...