All Vivo Cards are full XT Chips !! Fact!
Some, most newer Cards, cannot reach the XT-PE 520_560 Speed ! But with XT 500_500 Bios it should be no Problem!
The 16Pipes you can get 100% cause its the same "16Pipes Quality" like on a XT !
Theres not one Card out there with damaged Pipes cause the Flash or somewhat! 100% Succes..
With this you cannot make anything wrong ! Test the clock before you flash it !
You only can get a blackscreen after Flashing...not bad!
I suggest to use the Connect3D XT 500_500 Bios.. Vivo will match 500_500 Clock 99%! If not, you can edit a XT Bios with rabit 1.6 ,to use lower Clock..Or you use the Pro Bios, but with 16Pipes....
To flash it on 16Pipes you can use the modified flashrom with a XT Bios. Or you can go the "Gigabyte Way" with Gigabyte Flashtool and Gigabyte XT-PE Bios!
To test the safe max clock ,dont use ati Tool 0.23beta 6-8! Many X800 User report to low, wrong Scanning with this beta...Rendering Code produce Errors...
It gives to low MEM Clock! I actually use older 0.22final or AtiTrayTool 101.386 ,this will give you exactly the right max clockRates and is 100% safe.
But dont use find max Functions! Test it manually with Artifact Scan (i suggest AtiTrayTool 101.386 or AtiTool 0.22) !
After that make another Test for the Mem Clock with 3dm03 Ragtroll Test
Looping under max Settings and with no CaseCooling..! And also with MotheNature Test
for the GPU, Settings on max and in Looping mode for a few Hours!
So you find out a very good max ClockRate for your X800 Card what all Time is stable!
Do it....