There are several planar upgrades for Mod. 70/80 such as Turbo Board, PowerBoard,  Replay OEM planar   ( so called ) and such.  I got  my Reply upgrade planar together with associated manuals ( original for M80 and   a copy set  for M70 ).  Both manuals clearly states they are for  " PowerBoard ". So I refer  Mod.80 Replay  planar  with 4 SIMM slots and Mod.70 planar with 3 SIMM slots as " PowerBoard". 

  Mod.60/65/80  PowerBoard:  Please refer Louis's page  ( mirrored by William Walsh )
 

Mod. 70 PowerBoard: Also refer Louis's page  though it is titled as "TurboBoard",   the outline is exactly same with my PowerBoard.

PowerBoard Planar  Mod. 60/65/80

J1   Power connector J3   Keyboard J4   Mouse J11  Parallel J12  Serial J13  Video J14  VGA Enable/Disable J15  SPEED J16  CMOS J18  Speaker connector P1/P2,P4 P7 32bit slot P3    16bit slot P8    AVE 32bit slot U1    S82078-1B ( L4480900 ) U7    Socket 3 ZIF U17  IC DESIGNS 2028SC-B U20  Dallas DS1387 U22  APPIAN ADI/2 U23/29  FLASH  0214901/14801 U24  71G0438 U26  OSC 22.118MHz U36  10G4672 U44/45 02-17100/17000  U46/51  Additional VRAM socket U50  CIRRUSLOGIC CL-GD5434-HC-C U58/59 VRAM SEC KM416C256BJ-6 U31  SIMM socket #4 U39  SIMM socket #3 U40  SIMM socket #2 U41  SIMM socket #1 Q1    FR014 Q2    LT1085

  Jumpers
   Model 60/65/80
   J14  VGA;    1-2   Enable Planar VGA( CL-GD5434 )
                      2-3   Disable planar VGA

   J15  speed;   ON   =  25/50/75MHz 
                      OFF =  33/66/100MHz 

   J16 CMOS/ PassWord ByPass; 
   "The CMOS configuration is cleared by switching the jumper from one
     position to the other.   The jumper remains in its new position until the
     next time you decide to clear CMOS." 
 

   Model 70
   J11 ( locates beside 14.318 crystal ) 
   No indication on the PCB but the jumper is same as J15 of M80 P/B.
              ON   =  25/50/75MHz 
              OFF =  33/66/100MHz

   J14  CMOS/ PassWord ByPass;  same as J16 of M80 P/B 

   M70 P/B has not  a jumper for VGA Enable/Disable setting.  It's quite
   reasonable  because the planar has only 3 MCA slots.

CPU
M70/M80  PowerBoards are capable to handle DX2-50 to DX4-100, 5x86  and  PODP.    
DX4-100 and Cyrix5x86 can be used without an interposer. If you want to use
am5x86-133  you need to use an interposer.  I personally feel Cyrix5x86 is the
targeted  CPU for these  planar.

Manual says
" 486SX/2-50 *1  486DX/2-66, or 486DX4-100 processors ( standard options
at time of order);  along with supports for future OverDrive compatible processors. "

    note *1 is not listed in M80 manual . 
 

Cyrix5x86
Just put it on the ZIF socket directly and set J15 "speed" jumper unplugged. 
If you run DOS, Win3.1, Win9x  or NT4,  you'd better use appropriate cache programs 
to activate L1 cache  W/B feature. 
I've been using ET586.exe by Evergreen which is contained in et9603.exe  ( et9603.exe is
not  found at their site this moment. If you need it,  let me know. ) 

   et586.exe setting on my M80 P/B
   INSTALL=C:\ETI\ET586.EXE /PCR0=2  /CCR2=56  /CCR4=1D /PMR=3 /WBE

     You may delete  "/PMR=3" and  "/WBE" comments.

AM5x86/133-ADZ
I tested  am5x86 together with a PowerLeap interposer( and some Japanese made interposers).  
Am5x86 in 133MHz operation will give higher performance result under DOS and 
Windows95 bench programs than Cyrix5x86.  But I feel Cyrix is faster than am5x86. 

PODP5V83 ( PODP or P24T )
Runs nicely on the board.   L2 cache problems are reported here and there.  
I don't have  experienced any  trouble with  a 126K L2 cache pulled from  PC720  
( Japanese domestic 486 class hybrid  MCA-PCI system ).

EIDE interface
I vaguely remember that PowerBoard FAQ in Neo Interactive said that the board didn't  support ATAPI CD-ROM.  But actually I connected a Sony CDU-511 x8 drive on my M70 P/B and installed Win95 with the drive. 

SIMM 
Max. amount is limited to 64MB.  ( and actually  system will not recognize RAM  more  than 64MB neither Win95 recognize actual RAM beyond 64MB.  I don't think  himem.sys in PC-DOS7 will help. )

Video
Onboard CL-GD5434 is a nice chip.  You'd better use additional VRAM's and  expand to 2MB. 
Performance will be boosted with additional 1MB of  SOJ chips. 

L2 Cache
Haven't ever seen a genuine Reply option for this socket.  Socket itself is same with that of 9585 and Lacuna.    I have an 126KB L2 module pulled from  Japanese system which is called "L2 SuperCache".  It works nicely so far. 
 

P/B and SCSI /A
IBM SPOCK SCSI
I had no remarkable problem with this adapter. 
In order to use SPOCK SCSI under Win95, do not attach any IDE devices off from onboard IDE interface. 

F/W SCSI II/A ( Corvette ) 
Most possibly  Corvette may not  be properly configured on the board. So far I haven't ever  heard about successful installation. 

AHA 1640 
I failed to use and haven't heard any success report . 

Future Domain MCS700
Not yet tested but maybe OK. 

MS-DOS compatibility mode under Windows95;
System run in MS-DOS compatibility mode even you don't have IBM SCSI. 
    

OS compatibility other than Windows95
   

I've seen many defective M70/M80 PowerBoard planar. Seems like PowerBoard planar are  not so well designed as a MCA product.  If you get a good one,  you are just *lucky*.
I hope you will get a real Powerboard but not a  *WeakBoard*. 

Clock Up ( 8570  PowerBoard )
You can change the base clock from 33MHz to 40MHz if you are a good soldering iron man.
   click here

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