How to get higher multiplier than 12.5x on EPOX 8K7A mobo?

[gnawrot]

I have following items:
EPOX 8K7A with BETA BIOS 0923
AMD XP 1700+ TbredB unlocked - all L1 bridges are closed

I know that there are posts out there and I tried trick to blow 5th bridge of L3 but 8k7a mobo did not recognized my CPU even if I set on low multipliers. It did not work at all. I reconnected 5th L3 bridge and CPU was working.

I would like to get higher multiplier than 12.5x - preferably 15x. I believe that this 0310 CPU will handle it. CPU worked at 2075MHz at stock voltage using 166 FSB.

Thanks.

 

[johncar]

Originally posted by: gnawrot
I have following items:
EPOX 8K7A with BETA BIOS 0923
AMD XP 1700+ TbredB unlocked - all L1 bridges are closed

I know that there are posts out there and I tried trick to blow 5th bridge of L3 but 8k7a mobo did not recognized my CPU even if I set on low multipliers. It did not work at all. I reconnected 5th L3 bridge and CPU was working.

I would like to get higher multiplier than 12.5x - preferably 15x. I believe that this 0310 CPU will handle it. CPU worked at 2075MHz at stock voltage using 166 FSB.

Thanks.

http://www.beachlink.com/candjac/index.htm link to Workarounds article. Read about issues and workarounds, "esp with the 1700" which sets an "unbootable" Mobile 3X when you open just the 5th L3. Whole list of things to try....cause issue can be very mobo specific.
John C.

 

[gnawrot]

I looked at this site and it is kind of difficult to understand what they are talking about. I thought that there is a simple solution to get higher multiplier than 12.5 but I guess it starts to be mobo specific and might not be as easy as I thought. Thans anyway, johncar.

 

[gnawrot]

OK. I unlocked 3th and 5th L3 bridge and I get following speeds (all above 12.5x) but I don't get full range of multipliers:

13x - ????0 (most common whenever 5 bit on DIP switch on mobo is set to OFF)
15x - 11101 (1 means ON and 0 means OFF)
16x - 10101
16.5x - 00101
17x - 11001
18x - 01001
19x - 01111
20x - 00111
22x - 01101
23x - 10001

The system was posting correctly but I did not test stability because I was running at 100Mhz FSB and I am not interested to run at this FSB speed for most part.

The system could not come up at 15x133MHz - don't know reason yet - I increased core voltage to 1.6V.

I blew those bridge with 5V from spare Power Supply (easy - one spark and done).

Johncar any ideas - what else to do?

 

[johncar]

Originally posted by: gnawrot
OK. I unlocked 3th and 5th L3 bridge and I get.....

13x - ????0 (most common whenever 5 bit on DIP switch on mobo is set to OFF)
15x - 11101 (1 means ON and 0 means OFF)
16x - 10101
16.5x - 00101
17x - 11001
18x - 01001
19x - 01111
20x - 00111
22x - 01101
23x - 10001

The system could not come up at 15x133MHz - don't know reason yet - I increased core voltage to 1.6V
Johncar any ideas - what else to do?

First we convert your 1s and 0s to HI and LO signals. Looks like your 1 means LO signal and your 0 means HI signal on Multiplier signal bus.
This is different from normal 1 = HI, 0 = LO, but it's just nomenclature and you can change yours to comply with standard.
We print "your code" and compare to "actual signals" below to prove our point. H = HI, L = LO

Multiplier- Your Code- Actual HI/LO signals for .5X thru 8X bits.
15x - 11101 = L-L-L-H-H left to right = .5X, 1X, 2X, 4X, 8X bits
16x - 10101 = L-H-L-H-H
16.5x - 00101 = H-H-L-H-H
17x - 11001 = L-L-H-H-H
18x - 01001 = H-L-H-H-H remapped from 17.5X
19x - 01111 = H-L-L-L-H remapped from Mobile 3.5X
20x - 00111 = H-H-L-L-H remapped from Mobile 4.5X
22x - 01101 = H-L-L-H-H remapped from 15.5X
23x - 10001 = L-H-H-H-H remapped from 18X

Notice that in every case your 1 = LO and your 0 = HI...except for the last, rightmost, 8X bit which should be HI for all settings above 12.5X, but your code shows a 1 = HI for that bit where you show a 0 for the other 4 bit HIs. So even if you reverse your 1s and 0s to comply with standard nomenclature, we still have to explain that last 8X bit. Maybe that switch is "different", maybe it's different cause it "toggles" the Multipliers between the 12.5X and down and 13X and up ranges..(and where 12.5X is reset to 13X).
Anyway you can see a basic "correlation" between your switches' nomenclature and actual HI/LO signals. Check also with our Table of Settings in Workarounds article, O = Open = HI, C = Closed = LO.

Now for other real problems....
We notice you could not get 13.5X, 14X, 14.5X so we begin to wonder if that is like the problem in the article where people could not get 13X thru 14X but 15X and up was OK, (14.5X remaps to 21X). Read that section with the Red buffered logic circuit in the accompanying block diagram to understand what we're talking about. Your mobo might have that troublesome circuit for Tbreds.
To verify try 14X100MHZ, set L-H-H-L-H = 10011 your switch code. If it doesn't boot then you "might have" that circuit/problem. Then also note the particular workaround that KF came up with., where you "lock" the 4X bit LO and set 4X less than desired.

As to the 133MHz no boot problem, we have no clue. Could 15X133 be too much for the chip?? Does 13X133 boot???
John C.

 

[johncar]

gnawrot,
Was really late at night and we must of been sleepy...anyway....we
figured out what the "5th switch" does. Your mobo must be an older Duron/Tbird 4 bit mobo with no switch for the Palomino/Tbred 5th 8X Bit Value bit. Then your 5th switch must be for toggling between Auto/jumper-free mode and jumpers mode. So that when 5th switch is OFF it actually means that the "other 4 switches" are ignored = Auto/jumper-free mode and the Cpu boots at its default setting which now = 13X since you reset it there by blowing the 3rd and 5th bridges...and agrees with your data.

Then when that switch is ON the other 4 switches are enabled to "over-ride" the 1st 4 signals/lo bits set on the CPU...which is the User-defined/jumper mode.

Finally then, your data says you were using the "Set 8X Less than desired" technique...with the "inaccessible" 5th bit set HI manually, (when you blew the 5th L3).

So "all of your data" is now perfectly explicable....right???

In future refer to 1st 4 switch settings as H = HI = OFF, L = LO = ON, forget 1s and 0s. And refer to the 5th switch as Default/Auto/Jumper-free = OFF , 1st 4 bits User-Defined = ON.

So now really recommend to try 13X, 13.5X and 14X in User-defined mode to verify if you have the timing problem with that Red buffered Logic circuit. Here are the settings....
13X = L-L-H-L for 1st 4 switches/bits, 5th sw = User defined/ON
13.5X = H-L-H-L
14X = L-H-H-L
We expect no boots for these.

BTW, you should read the Multiplier Code article, 1st part, to learn AMD's Multiplier code with the 3X Offset and remappings. You'll be lost if you don't, and it's not rocket science...print out the Algorithm and Table of settings to have them handy when you're doing settings.
John C.