There are many ways to overclock your processor. The most efficient and reliable way is to overclock in BIOS. But there are other programs that can do this.
Here is some (Note: Some are stability tools but are also overclockable)
(Taken from MajorGeeks.com)
Active CPU - [2002-01-22 | Freeware | 455 Kb | Win 9x/ME/NT/2K | 24453 | 4.58 ]
Show graphical use of your CPU's activity.
AMD Power Monitor - [2006-11-24 | Freeware | 8.3 Mb | Win All | 19836 | 4.52 ]
Monitor your AMD frequency, voltage, utilization, and power savings.
Amn Refrigerator - [2002-03-28 | Freeware | 103 Kb | Win 9x/ME | 28106 | 4.27 ]
Cool down your CPU during idle times.
Another Task Manager - [2002-01-22 | SHAREWARE | 158 Kb | Win 9x/ME | 25318 | 4.75 ]
Monitor processes and threads, their CPU usage...
Athlon CPU SoftCooler - [2004-12-24 | Free | 568 Kb | Win All | 69122 | 4.51 ]
Take control your AMD Athlon processor.
BinaryWork CPU Controller - [2002-01-22 | Shareware $36.90 | 573 Kb | Win 9x/ME/NT/2000 | 20281 | 3.75 ]
Have total control over your processor.
BurnIn64 - [2004-04-16 | Shareware $18.95 | 315 Kb | Win XP | 9725 | 4 ]
A burn-in tool designed for AMD64 architecture.
Central Brain Identifier - [2007-09-08 | Freeware | 274 Kb | Win All | 153534 | 4.71 ]
A free AMD processor identification and monitoring utility.
CPU Burn-in - [2003-06-25 | Freeware | 7 Kb | Win All | 42961 | 4.17 ]
A stability testing tool for overclockers.
CPU Eat 'n' Cool - [2005-05-16 | Freeware | 206 Kb | Win NT/2K/XP/2003 | 49318 | 4.54 ]
Cool the CPU when it is busy.
CPU Hi-t Professional Edition - [2002-06-03 | Freeware | 2.9 Mb | Win All | 22546 | 4.33 ]
Designed for testing CPU and stability.
CPU ID - [2004-08-01 | Freeware | 47 Kb | Win All | 69761 | 4.51 ]
Displays all the available information about your processor.
CPU Indicator Screen Saver - [2002-01-22 | Freeware | 314 Kb | Win All | 18161 | 4.8 ]
Watch your CPU usage and history in a screensaver.
CPU Load - [2004-04-11 | Freeware | 1 Mb | Win XP/2K/2003 | 15964 | 4.25 ]
This little tool will let you monitor your CPU Load.
CPU Speed Adjuster - [2006-06-27 | Freeware | 24 Kb | Win All | 9837 | 4.66 ]
Slow down your PC so that you can run all your old programs.
CPU-Charge - [2002-01-22 | Shareware $12.00 | 2 Mb | Win 9x/ME/NT/2000 | 19285 | 4.25 ]
Optimizes and cools your CPU as well as...
CPU-Z - [2007-09-04 | Freeware | 488 Kb | Win All | 299543 | 4.60 ]
Utility that provides some information on your CPU.
CPUFSB - [2006-10-20 | Shareware $13.00 | 1.01 Mb | Win All | 270988 | 4.74 ]
Small version of CPUCool for changing FSB.
CpuIdle 9x,ME - [2003-09-11 | Shareware $20.00 | 464 Kb | Win 9x/ME | 15645 | 4.75 ]
Lower temperature and increase the life of your processor.
CpuIdle Pro for NT,2000,XP - [2003-09-11 | Shareware $20.00 | 565 Kb | Win NT/2K/XP | 46223 | 4.86 ]
Lower temperature and increase the life of your processor.
CpuiDMax2 - [2003-06-30 | Freeware | 361 Kb | Win All | 14737 | 3 ]
Freeware program that provides information on your CPU.
CPUInfo - [2004-12-13 | Freeware | 309 Kb | Win All | 35824 | 4.5 ]
Shows detailed information about the processors on the mainboard.
CPUkiller - [2003-10-23 | Shareware $19.00 | 687 Kb | Win All | 16196 | 4.75 ]
Slow down your processor for older games or applications.
CpuLower - [2002-01-22 | Freeware | 164 Kb | Win All | 20643 | 4.46 ]
Slow down your PC to play older games.
CPUsage - [2005-12-05 | Freeware | 455 Kb | Win All | 4229 | 5 ]
Shutdown or restart your computer if the CPU stays at a certain load for a certain period of time.
CPUSpy - [2005-08-19 | Shareware $6.95 | 52 Kb | Win 9x/ME/2K/XP | 12799 | 3.5 ]
Tests and displays CPUID data such as cache details, processor features and much more.
CPUUsage - [2002-03-06 | Freeware | 483 Kb | Win NT/2K/XP | 10795 | N/A ]
Free tool that displays the cpu load as a tray icon image.
CrystalCPUID - [2007-09-25 | Freeware | 745 Kb | Win All | 28533 | 3.41 ]
A CPU identification utility.
GCPUID - [2007-05-18 | Freeware | 539 Kb | Win All | 30387 | 3.23 ]
A freeware utility that shows you information about your CPU.
HCPUID - [2002-06-25 | Freeware | 230 Kb | Win All | 16286 | N/A ]
Displays CPU information details and RAM SPD data.
Hnet Info CPU - [2002-11-18 | Freeware | 2.9 Mb | Win All | 12799 | 5 ]
Provides 126 bits of detailed information about your processor.
Intel Application Accelerator - [2002-11-21 | Freeware | 1.9 Mb | Win All | 61118 | 4.63 ]
Reduce the storage sub-system bottleneck
Intel Application Accelerator RAID Edition - [2004-08-04 | Freeware | 3.4 Mb | Win XP/2K | 17592 | 4 ]
Support for high-performance Serial ATA RAID 0 arrays on select Intel® 865 and 875 chipset.
Intel Processor Frequency ID Utility - [2004-11-24 | Freeware | 850 Kb | Win All | 33339 | 4.21 ]
Identify and determine if your Intel chip is running at proper frequency.
Intel® Processor Identification Utility Windows Version - [2007-09-13 | Freeware | 1.02 Mb | Win All | 20520 | 4.78 ]
Identifies the Intel® processor inside a system.
KCPUCooler - [2002-01-22 | Freeware | 67 Kb | Win 9x/ME | 14749 | 3.66 ]
Shutdown your cpu when it is not used.
MCS CPU Benchmark V5 - [2005-11-27 | Freeware | 2.4 Mb | Win All | 10326 | 3.71 ]
Assessment of the performance of your processor in general home environment usage.
MegaHertz - [2002-10-31 | Freeware | 59 Kb | Win All | 25446 | 3.8 ]
Small utility to calculate the actual clock speed of your CPU.
Overclocking Calculator - [2002-01-22 | Freeware | 145 Kb | Win All | 49545 | 4.75 ]
Calculates CPU speeds, PCI bus speed and...
PCBoost - [2007-10-21 | Shareware $9.40 | 964 Kb | Win All | 73831 | 1.75 ]
Optimize your computers performance and make your computer faster.
Powertweak - [2002-01-22 | Shareware $25.00 | 1.4 Mb | Win All | 28124 | 5 ]
A hardware optimization software.
Priority - [2002-03-23 | Freeware | 322 Kb | Win All | 19027 | 4.77 ]
Changes the CPU priority of running programs to high.
Process Tamer - [2007-08-20 | Freeware | 2.23 Mb | Win All | 15333 | 4.44 ]
Reduces the priority of cpu overloading applications.
Rain 1x - [2002-01-22 | Freeware | 123 Kb | Win 9x | 19708 | 4.82 ]
CPU cooler designed for overclockers...
Rain 2x - [2002-01-22 | Freeware | 121 Kb | Win 9x | 36917 | 4.51 ]
CPU cooler designed for overclockers...
RawPower - [2002-01-22 | Shareware $20.00 | 314 Kb | Win 9x | 18877 | 4.5 ]
CPU optimization software.
RightMark CPU Clock Utility - [2007-10-05 | Freeware | 564 Kb | Win All | 52026 | 4.22 ]
On the fly adjustment of the cpu multiplier, voltage level and more.
RMClock utility - [2005-03-04 | Freeware | 149 Kb | Win All | 38099 | 4.40 ]
Realtime frequency monitoring and adjustment to cpu multiplier and voltage level.
See Saw Pro - [2002-01-26 | Freeware | 61 Kb | Win NT/2000 | 11849 | 4.11 ]
A utility to fine tune dual-CPU workstations.
SoftFSB - [2002-01-22 | Freeware | 113 Kb | Win 9x | 83456 | 4.80 ]
Change the FSB without restarting.
Speed Gear - [2004-05-20 | Shareware $29.95 | 543 Kb | Win All | 34691 | 4.66 ]
Can be used to adjust your Windows system speed.
SpeedswitchXP - [2006-08-28 | Freeware | 788 Kb | Win XP | 25402 | 4.65 ]
Allows switching of the frequencies of mobile Intel and mobile AMD CPUs under XP.
ThrottleWatch - [2005-02-09 | Freeware | 156 Kb | Win All | 16873 | 4.93 ]
Monitors and displays both CPU load and throttling of Intel chips.
Toast - [2002-02-20 | Freeware | 268 Kb | Win All | 62262 | 4.57 ]
Torture test and burn in your CPU.
Tom's Hardware Guide Clock - [2003-06-05 | Freeware | 48 Kb | Win All | 25348 | 4.66 ]
Designed to detect dynamic overclocking in realtime.
TurboCPU - [2005-09-08 | Shareware $22.00 | 855 Kb | Win XP/2K | 10527 | 4.53 ]
Increase or reduce CPU speed spent to executed processes.
VCool - [2002-12-02 | Freeware | 36 Kb | Win All | 36640 | 4.59 ]
Utility that cools your Athlon/Duron processor.
VIA HyperTransport Analyzer - [2003-09-12 | Freeware | 137 Kb | Win All | 15761 | 4.5 ]
Displays the actual bus width and frequency between the CPU and Chipset.
Waterfall Pro - [2002-01-22 | Freeware | 1.2 Mb | Win 9x | 43024 | 4.41 ]
Protects your PC and cools down your processor.
WCPUID - [2004-04-05 | Freeware | 263 Kb | Win All | 234975 | 4.70 ]
Displays the CPU information of your computer.
Win2000 Launcher - [2002-01-22 | Freeware | 457 Kb | Win NT/2K/XP | 32211 | 4.82 ]
Application booster for Windows 2K and Windows XP.
WinCooler - [2002-01-22 | Freeware | 1.2 Mb | Win All | 17445 | 3.14 ]
A low power idle process that cools your cpu.
