Oh hell it'll take 2.6 all year long with good cooling, it's cheap, push it....

I had a 2.4 volt 450 ctx that needed 2.6 for 500 or 525 but that's all and I tried up to 2.8 and 2.9 with and ALPHA.

Now im in SS7 with this!

System Description
TYAN S1590 (Hacked latest BIOS allows K63+ recognition).
192 MB CAS2 SDRAM (Running in 4 way interleave courtesy of WPCREdit and set.)
K63+/450 @ 5.5x100 using 2.1vre and original ALPHA for S7 (Will do 600 @ 2.4 but running extended burnin first, these are expensive now)
Mid Tower Case with 250w PS
APC SmartUPS 620 Connected via Serial Port w/Powerchute Plus 5.2
6.5 UDMA 7200 RPM, 3.5 UDMA 5400 RPM
50X CD
8X8X32 CDR/RW
Aureal Vortex SQ2500 With 4 Speaker Surround Setup
AOpen FM56H PCI Modem
GeForce 2MX @ 210 core 205 mem Custom Mounted Fan
Panasonic KXP-4410 lazer
Canon BJC5100
FM Radio (No joke! I love this thing!)
Extra LPT Card (runs both printers at once)
Sidewinder 3D PRO (anybody want this prick!)
2 Intake and 2 Exhaust Fans
Logitech Trakman Marble + (Scroller)
LitOn Ergo Keyboard (MS Natural Clone)
17" Pixie (actually pretty good)

USB Stuffies:
4 Port Hub
Visioneer 3100 scanner
IBM Webcam
Hanspring Visor DLX Cradle
Logitech RumblePad (too cool for 30 bucks!)