Macpro 3,1 and 4,1 install issues

hi everybody, happens find 2 mac pros, on flea market 50 usd each. first 3,1 , second 4,1 without memory, hdd , graphic card. 3,1 has missing riser cards found on ebay @ 40usd 4 gb ram on them. bought graphic card pc, hd5770 , reflash of netkas community. went smoothly , boot screen. try configure 3,1 , install softwares on it. make usb stick el capitan , install scratch. went until white screen of death. after can boot on safe mode. i've tried everything, cannot boot normally. noticed if install snow leopard dvd installs , computer boot normally. if try make update went until10.6.8. after 10.6.8 update white screen of death. i've tried install mavericks, yosemite , el capitan scratch same result, white screen. tried mac pro 4,1 same graphic card , same result. install windows 7 on macpro 3,1 , seem work ok, test graphic card on windows , has no issues. run apple hardware test , no problem found. please help, can tell me how can solve thing. thank you.

 

disconnect wired , wireless (bluetooth) peripherals except keyboard, mouse, , else necessary reboot.
1) try safe boot: boot holding shift
2) try zapping pram (nvram) , smc reset.
3) pram: boot while holding command + option + p + r until mac reboots:
smc:

1. shut down mac.
2. unplug mac's power cord.
3. press , hold mac's power button 15 seconds.
4. release power button.
5. reconnect mac's power cord.
6. wait 5 seconds.
7. start mac pressing power button.

some additional info:
https://appletoolbox.com/2014/09/mac-fix-white-screen/

luck.

 

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