PLL hardmod ???

[Retrorockit]

I'm trying to learn, but what I'm wanting to try has never been done ASFIK.
There used to be a PLL hard mod that socket 478 laptop guys used to run a pull down resistor so the PLL wouldn't be locked to some selected fsb value.
I've studied the datasheet for my PLL and found the relevant pin. A high value from the BIOS latches my PLL to 266fsb maximum. On LGA775 thay defeat the resistor mod by runnning a PCI frequency out put on the same pin. My question is if I lifted that pin, and put a diode so the PCI output was still there, would the lack of any low signal input cause an error, or would it just pass as a low signal and alllow the FSB to be unlocked?
This is for an XPS 410 overclocking project. It's Dell, it's BTX, it's P4 era.
But I've had the related Dimension E520 to 4GHz with a QX6800 in 2015. I've got a few more tricks up my sleeve this time. I think I can reset this bit with Clockgen. But I'm already doing my multipliers and Voltage with another program. So i'm a little concerned about being able to save this setting.

[Retrorockit]

Re: PLL hardmod ???

I learned a few new abreviations and looked further down the datasheet and figured it out.
Vil = min .3V /max .8V
So there does need to be a signal Voltage to set the TME pin to low.

[RJARRRPCGP]

Re: PLL hardmod ???

QX6800?! Isn't that one of the 65nm Quads?! Those at 4 Ghz are likely to use more watts than an FX, possibly a lot more than an FX9590! That will dwarf a Prescott there!

Heck, most 65nm Core 2 Quads at 3.6 pull 250 W or the like alone!

[Retrorockit]

Re: PLL hardmod ???

Here's my CPUZ of my MicroBTX Dimension E520. QX6800 4GHz.
http://valid.x86.fr/bg4n0r
It was in 2nd place for a couple years in 2015. I got bumped by a few MHz in 2017. The full multiplier overclock, and old capacitors kept me from responding.
The Dimension 9200/XPS410 can use Setfsb for smaller increments, and new caps should let me maybe go a little higher. I mentioned at OCN LGA775 Club that BTX was designed for higher clock speeds in LGA 775 than ATX and got jumped by some ASUS fanboys.
But the 4 phase VRM of the XPS210/410,Dim. 9200/9200C/E520 with some heatsinks is pretty stout. BTX is all about VRM cooling and high clock speeds.
I also have some better coolers and fans than I had then. I was running the 2 motor Delta GFB121VHG 3.4A. fan off of a Molex to free up some power on the 18A rail of the Dell PSU. I'll be running a single rail EVGA PSU that has enough on the 5V. rail to run one of these.
Throttlestop can be hacked to OC just 2 cores which will annoy hell out of the ASUS boys. But actually makes sense for a retro gamer since SSE3 is the highest instruction set then anyway.
But 130W PentiumD CPUs and 3.8 GHz P4 were what this was designed for.
I didn't know it at the time but I could have underclocked the fsb with Setfsb, added another multiplier and come back up. But a 12 year old computer, with known bad caps, that had been OC was on it's last legs.
For cheap thrills the Optiplex 745 can OC also, but the 3 phase VRM holds it back about 1 multiplier.