CPU-Z #3 on hwbot by evil ukrainians, old good celly.

[TiN_]

Most of us wants top speed. Some of us need top mhz so badly, and forget about performance at all. Just RAW MHZ . At that ancient times, when Intel failed to release 4GHz stock CPU, hardware lurkers with LN2 already got better clocks. Waaaay better...

These journey is available to everybody. Just need some time, some knowledge, and a lot of LN2

Xtremelabs.org team benched some oldstyle cedars, and we found good one to try for some CPU-Z rank movement.

Pot Xtremelabs.org MAGNUM Cu
Intel SL9KL C356
ASUS P5B DLX С2
1024M Crucial Ballistix 1:1
3Dfx Voodoo Rush PCI
WinXP with viruses
CoolerMaster RPP 700W

To work on high freq big voltage is essential. As big as 2 volts. But on famous P5B Deluxe engineers limited max voltage to ~1.92V. To implement this FBRTN line is used on PWM-controller from Analog Devices, ADP3198.

To get rid off this limit we developed some easy mod, called tuning OVP (OverVoltage Protection). For this we need to shift voltage on FBRTN up. Known to any bencher resistor mod is unusable here, because we need to increase resistance below GND, not decrease. Where to get extra? All OVP mods here at XS, and not only limited to hooking up +3.3 from PSU to FBRTN via VR. Of course, this way it will work, but advanced people know, that high-power +3.3v line direct from PSU can fluctuate a lot, make excessive noise, voltage ripple and other bad thing for extreme clocks.

I've made standalone low-noise DC-DC convertor, to get clean +3.3v specially for OVP. To improve stability on output I've used high-quality caps Nippon Chemi-con 390uF 6.3V LowESR and allmigthy OSCON SP 1000uF 4V. Because it's not switching DC-DC, just simple LDO, no matter about ESR, so just single caps is enough.

Schematics of my mod:



U1 - our DC-DC (on pic is LM317 but actually used LM1117-3.3 fixed), C2,C3 - caps, R2 - VR to finetune OVP, if needed. Resistance of original curcuit with FBRTN to GND is 20 ohm, and by adding clean +3.3 via 500ohm extra VR we add +172mV to FBRTN level. This allowed us to have Vcpu = 1.92 + 0.17 = 2.1 V.

On photo all these stuff is mounted on tiny PCB and glued to superio chip Winbond near the corner. You can see two wires going to GND and +5V on 24-pin ATX connector.



And with this mod we used simple FB Vcore mod and Vdroop, which was made by teammate Nick.ua. Nothing interesting here, all from widely available guides from net.

Attention. Max voltage swing on FBRTN = +-300mV. All above or below will render mobo dead! Recheck everything 10 times before power up.

Then everything as usual for LN2 sessions, insulation , prepare and launch. For thermal measurement Fluke 87V was used. MaJ0r keep temps around -170





After hour of tries and checks, system froze all over around . Even my USB stick with 8G validations got some frost.



Best result so far:



8127.5MHz raw clock, -170°C, 2.10V

After that we remove pot with cold and left system defrezzin.



Overclocked by Xtremelabs.org team, Nick.ua as overclocker, mobo prep and OVP mod by me, MaJ0r controlled temps with LN2.