Dual Socket-370 Celeron's
With Socket-370 to Slot-1 Convertor Card
A-MAX Socket370 to Slot1 conversion card
Until recently, most of us had no real use for the Socket 370 PPGA Celeron's, since they need a new Socket-370 based motherboard. However we are now starting to to see Socket 370 to Slot 1 conversion cards available for purchase, which allow you to run a new Socket-370 based Celeron in a Slot-1 motherboard..
A-MAX Socket-370 to Slot-1 Conversion Card
The above is a Socket370 to Slot1 conversion card from A-Max Technology.
Since I got a hold of the conversion card, I went out to buy the PPGA (Socket-370) Celeron to go along with it. I picked up a retail Celeron 300A, ID SL35Q, Stepping ID665. I had no problems with running this processor at FSB 100MHz with the normal 2.0V, however it will need some 'kick' (i.e. increase in core the voltage), if it is to be run at 504MHz. If you get lucky, yours may run at 504MHz without increasing the voltage.
Now that we have it working and overclocked fine, this brings us to the next issue - dual operation. Again, as in the Slot-1 Celeron, BR#1 is reserved (according to the Celeron's data sheet), so it will not work in a dual-processor system right out of the box. In addtion, A-MAX's Socket370 to Slot1 conversion card has B75 pin/contact documented as "N/C", making the modifications even more difficult.
Considering the fact that we simply don't know where the BR#1 pin is located on the PPGA package, and we don't know whether this pin really EXISTS or not, we just gave up on making them work in dual operation...
...well, that was my feeling, until I received great news from Mr. Christoper Kuperman that he'd succeeded in making his Socket-370 Celeron's work in dual operation using MSI's Socket-370 to Slot-1 converter board (MSI MS-6905 PPGA Celeron Converter).
The Challenge with MSI's MS-6905
So I then went out to Akihabara to get MSI's MS-6905 PPGA Celeron Converter Board.
According to Mr. Kukperman, the PPGA Celeron's BR#1 pin corresponds to the AN15 pin on the convertor board. He said that it may work if we connected B75 to AN15, and pulled it up with Vtt voltage.
B75 on the MS-6905 is obviously conneted to somewhere, and if the line went straight to AN15, no modification would be required for the dual operation of PPGA Celerons. So we crossed our fingers, and tried it out. It did not work. Our voltmeter also indicated that it was not connected to AN15.
Then where is B75's line going? It turned out that B75 is connected to the RN17 register directly which means it is being pulled up by the Vtt voltage.
That means that the only modification required is to connect AN15 to B75 to allow PPGA Celeron's to work in dual operation.
If you follow the pattern of MS-6905 from the B75 pin, there is a hole through the board (through hole??). Make the connection from AN15 to this hole/pattern with the jumper wire. It does not matter how thick the wire is. I used the same wire as before, but it is definitely recommended to use wire with plastic insulation.
Connecting AN15 and B75
Dual with PPGA & SEPP Celerons
That's it for the modifications. Now the test.
We now fitted the PPGA Celeron 300A into the modified MS-6905, and placed it into the CPU slot on the motherboard. The remaining Slot is fitted with the modified SEPP (Slot-1) Celeron.
The motherboard recognized 2 processers. Windows NT 4.0 also recognizes PPGA Celeron 300A, stepping ID:665 as the CPU1.
Both CPUs are stable @463MHz with normal core voltage of 2.0V.
Some Thoughts On Conversion Cards
That's it! MUCH simpler to do than modifying the Slot-1 Celeron's. And the good thing about this is that there is no having to worry about making a mistake - if you accidentally ruin your convertor card, you can go out and buy another one for 15 bucks. Although the Socket-370 based Celeron plus the convertor card will cost a bit more than a Slot-1 based Celeron, this is definitely the way to go if you are looking into making a dual-processor system.
MSI's MS-6905 lead us to the successful dual operation, however applying these same modifications to the A-MAX card DID NOT WORK. Although there are many other convertor cards currently available, we can only say (for now) that these modifications work with the MSI MS-6905.
This modification information was made possible with the information from Mr. Christopher Kuperman. We would like to thank Mr. Christopher Kuperman for supplying us with the vital information regarding the BR#1 for Dual operation with PPGA Celerons. Without the information from him, these modifications would have taken much longer to discover.
By: Tomohiro Kawada