So, you want to overclock an X61T?

processor FRU planar serialno stock VID/FID idle draw min VID (FSB200, one core) min VID (FSB200, both cores) min VID (FSB266, one core) min VID (FSB266, both cores)
IDA HFM LFM SLFM IDA HFM LFM SLFM IDA HFM LFM SLFM IDA HFM LFM SLFM IDA HFM LFM SLFM
12. L7500 SLA3R 42W7818 48.4B404.011 1ZDXD7921KD 0925081c0615880b5.70W 0911080e060b880b 091f0816060b880b --0819060d880b
2014 66 3
2. L7500 SLAET 42W7818 48.4B401.011 1ZDXD81Z1BK 0925081b0615880b5.70W 0911080c060b880b 09200816060b880b --0818060c880b
2015 55 3
11. L7500 SLA3R 42W7818 48.4B404.011 1ZDP778S1HC 0925081b0615880b5.70W 0911080d060b880b 091e0816060b880b --0819060d880b
2014 75 2
14. L7500 SLA3R 42W7818 48.4B401.011 1ZDP777Y1XH 0924081a0615880b5.64W 0910080d060b880b 091d0815060b880b --0818060d880b
2013 75 2
5. L7500 SLAET 60Y4030 48.4B401.021 1ZHKW0BJFUS 0925081a0615880f5.04W 0911080f060f880f 091f0816060f880f --0818060f880f
20>11 64 2
9. L7500 SLAET 43Y9032 48.4B404.011 1ZDP778S1HC 0925081b0615880b6.36W 0912080e060b880b 091e0816060c880b --081a060e880b
1913 75 1
3. L7500 SLAET 43Y9032 48.4B401.021 1ZF3S87Y2W2 0925081c0615880b4.80W 09160810060b880b 09220818060d880b --081d0610880b
1512 34 -1
15. L7500 SLAET 42W7818 48.4B401.011 1ZDXD81Z1F6 0925081b0615880b5.70W 0912080f060b880b 09200819060e880b --081c0610880b
1912 52 -1
8. L7500 SLAET 42W7818 48.4B404.011 1ZDXD7OP1J6 092208180615880b5.88W 0913080f060b880b 091f0817060d880b --081a060f880b
159 31 -2
7. L7500 SLAET 60Y4030 48.4B401.021 1ZGR909AFU1 0925081c0615880f4.62W 09160811060f880f 0924081b0610880f --081f0612880f
1511 11 -3
6. L7500 SLAET 43Y9032 48.4B401.021 1ZEYR92A1MF 0925081c0615880f5.28W 09170812060f880f 0925081b0610880f --081f0612880f
1410 01 -3
13. L7500 SLA3R 42W7818 48.4B401.011 1ZDP777Y1XL 092108180615880b5.76W 0911080d060b880b 091d0814060b880b ----060d880b
1611 44
4. L7700 SLAES 43Y9034 48.4B401.021 1ZF3T89H1JZ 0a25091a0615880b5.28W 0a15090e060b880b 0a160911060b880b 0a24091b060c880b --------
159 1-1
1. L7700 SLAES 42W7845 48.4B401.011 1ZE3E81S1MC 0a25091a0615880b5.58W 0a14090f060b880b 0a170912060b880b 0a24091b060b880b --------
148 1-1
16. L7700 SLAES 43Y9034 48.4B401.021 1ZF3T8BB22J 0a25091b0615880b5.64W 0a160910060b880b 0a180913060b880b --091d060d880b --------
138 -2

Motherboards from the test are sorted above roughly in order of suitability for FSB 200->266 overclocking via the clockgen pin7 BSEL hack.

Lines in red are motherboards that failed a quick stability test consisting of the first seven linear equation sets from a standard 64 bit linpack run (about two minutes of computation time) with the fan at max and speedstep on automatic. In practice, this resulted in the processor running entirely in HFM at stock voltage once the test began.

'min VID' is the lowest VID at each multiplier that completed the linpack run successfully; it is not a good measure of overall stability, but it produced consistent, comparable results.

The number under various undervolted VIDs is the difference between the stock VID for that multiplier and the experimentally determined minimum VID for that test. A negative number means that multiplier would fail at stock voltage.

Entries listed as '--' indicates the processor was not able to complete the test for that multiplier at the maximum available software configurable voltage, or was unable to boot at all.

Motherboard 10 is not on this list; it was stupidly sacrificed to VRM mod testing before collecting detailed overclocking data. Hovever, it did pass the basic linpack stability test after FSB200->266 modding and before the VRM mod.

All of the L7500 motherboards crashed attempting to use overclocked dual-IDA (with the exception of mobo 10 after the VRM mod).

None of the L7700 motherboards were able to boot with both cores active (BIOS setting) after modding.

The tests in this table do not reflect any hardware voltage boosts or other modifications.