a7m266 wire tricks

Here're some pictures showing an alternative way of changing Tbred multipliers on A7M266 using wire tricks. I've used a thin wire from an 80-conductor IDE cable to reset a bit value high by connection to VCC/Vcore, or low to VSS/ground.

Although this trick also works for Tbred A, it is easier to use on Tbred B 1700, 2100, 2400 and 2700 since bit values 0.5x-4x are reset low by default and/or by interference from A7M northbridge circuit. Specifically, opened L3#3 and L3#4 (bit values 2x and 4x) in Tbred B which are set high by default, produced low signals in A7M. Thanks to P@N, Apa and StormyandCold (amdmb forum) for their works on Tbred 1700, 2100 and 2400. Thanks also to Monge (amdmb forum), a high 0.5x bit value (L3#1) in a 2200 Tbred B is apparently not affected, so that an opened L3#1 still gives a high signal in A7M. With Tbred B 1700, 2100, 2400 and 2700, one needs only to reset bit values high to VCC/Vcore to obtain a specific multiplier.

Tested an unlocked 2400+ XP-M (aqyfa 0343wpmw) on A7M266. Using 1.75vcore and without any mod, the CPU post as 11x, and was detected as a "1700+" with 512k L2. The CPU didn't post as 6x as one would expect from the opened 2nd and 3rd L3s. This means when the 8x signal was low (without mod), the signals on the 2nd and 3rd L3s were also low despite the opened L3 bridges, and the CPU ran at 11x. When the multiplier was set at 13x (an25 and aj27 high), the CPU ran as 14x, and a 15x setting (al25 and aj27 high) gave 16x, meaning when the 8x bit was high, the signal on the 2nd L3 was also high, but the signal on the opened 3rd L3 remained low at the above vcore setting.

Some wire connections are shown below. For example, to run 13.5x, connect an27-am26, an25-am26, and aj27-ah26 (0.5x, 2x and 8x high) and al27-ak28 (1x low) using phone wires which are thinner than those from IDE cables. These connections may also work for mobile 2500+ and 2600+.

Multiplier	0.5x an27	1x al27	2x an25	4x al25	8x aj27
13.0x	nc	ak28	am26	nc	ah26
13.5x	am26	ak28	am26	nc	ah26
14.0x	nc	nc	am26	nc	ah26
15.0x	nc	ak28	nc	ak26	ah26
16.0x	nc	nc	nc	ak26	ah26
16.5x	am26	nc	nc	ak26	ah26
17.0x	nc	ak28	am26	ak26	ah26

nc = no connection

Alternatively, CPUMSR or CrystalCPUID enables XP-M multiplier change on-the-fly on A7M266. Register 44 bit 0 was set to 1 first with Wpcredit.