Understanding the Celeron

The Celeron we’re going to be talking about here is what is commonly known as the Celeron A, available in clock speeds ranging from 300MHz to 433MHz, the Celeron A boasts a heavy feature set that explains its high-end performance, at a low-end price. The Celeron A is based on what was internally referred to by Intel as the Mendocino core, a 0.25 micron processor with 32KB of L1 cache, and 128KB of L2 cache integrated into the die of the processor, in order to cut costs while improving performance.

The Celeron is not frequency locked, meaning it can be overclocked through the use of higher Front Side Bus (FSB) frequencies, however it is multiplier locked meaning that higher clock multipliers cannot be used to overclock the CPU. Currently, all Celeron processors operate, officially, using the 66MHz FSB frequency, meaning that they are prime candidates for use on motherboards based on the newer Intel BX/GX and VIA/SiS Slot-1 chipsets, as well as on the older Intel LX chipsets, so don’t throw those old investments out just yet. Intel will eventually make the move to the 100MHz FSB with the Celeron family, but for now, the 66MHz FSB of the Celeron isn’t providing any major bottlenecks for the processor. More importantly, its backwards compatibility with older chipsets (440LX) make the Celeron one of the most backwards compatible processors Intel has ever released, a bit disappointing actually.

One of the reasons for the incredible popularity the first Celeron processors attained was the ability of the 300MHz parts to be overclocked to an incredible 450MHz, simply by using the 100MHz FSB in conjunction with the processor’s 4.5x clock multiplier. The soon-to-be classic 300A to 450MHz overclock gave many users the false impression that all future Celeron processors would be equally as overclockable, however in actuality, with every release after the original Celeron 300A, overclocking the CPUs became increasingly difficult. The reason behind this is simple, according to Intel, the theoretical limit of the Mendocino core, under their current manufacturing process, is approximately 550MHz. The success of the original Celeron 300A was simply due to Intel’s unusually high yield on the processors, meaning that the quality of the CPUs manufactured was high enough that a 300MHz part would reliably operate at 450MHz. As you’ll notice by the chart below, the overclockability of all Celeron CPU’s after the 300A seems to drop off sharply as you approach the 450MHz mark, for the same reason illustrated above, you’re approaching the physical limit of the Mendocino core.  This doesn't mean that you will never see a Celeron overclock up to and beyond 500 - 550MHz, it simply states that the odds are definitely against you if you're trying to accomplish just that. 

Celeron Comparison

  Clock Multiplier Rated Clock Speed FSB Realistic Overclocked Speed FSB
Intel Celeron 300A 4.5x 300MHz 66MHz 450MHz 100MHz
Intel Celeron 333 5.0x 333MHz 66MHz 375MHz 75MHz
Intel Celeron 366 5.5x 366MHz 66MHz 458MHz 83MHz
Intel Celeron 400 6.0x 400MHz 66MHz 450MHz 75MHz
Intel Celeron 433 6.5x 433MHz 66MHz 488MHz 75MHz

The worst overclocker?  The Celeron 333, the best?  The good ol' 300A, unfortunately the supply of 300A's that work at 450MHz is scarce, and seems to be limited primarily to PPGA Celerons alone, with the amount of overclockable SEPP 300As very limited in quantity. 

The Test

The Socket-7/Super7 Test System Configuration was as follows:

  • AMD K6 233, AMD K6-2 300, AMD K6-3 450 (engineering sample)
  • FIC PA-2013 w/ 2MB L2 Cache
  • 64MB PC100 SDRAM
  • Western Digital Caviar AC35100 - UltraATA
  • Matrox Millennium G200 AGP Video Card (8MB) - All other Benchmarking
  • Canopus Pure3D-2 Voodoo2 (12MB) - Glide Tests
  • Canopus Spectra 2500 AGP TNT Video Card (16MB) - OpenGL/Direct3D tests
  • VIA AGP GART Drivers v2.9
  • VIA Bus Master IDE Drivers
  • VIA PCI IRQ Remapping Drivers

The Pentium II comparison system differed only in terms of the processor and motherboard in which case the following components were used:

  • Intel Celeron 300, Intel Celeron 300A, Intel Celeron 333, Intel Celeron 366, Intel Celeron 400, Intel Celeron 433, Intel Pentium II 400, Intel Pentium II 450, Intel Pentium III 500
  • ABIT BX6 Revision 2.0 Pentium II BX Motherboard & ABIT BM6 Socket-370 Celeron BX Motherboard

The Pentium Pro comparison system differed only in terms of the processor and motherboard in which case the following components were used:

  • Intel Pentium Pro 200 (256KB L2), Intel Pentium II OverDrive 333 (512KB L2)
  • Octek Rhino P6 Pro Socket-8 FX Motherboard

The following drivers were common to both test systems:

  • MGA G200 Drivers v1677_426
  • nVidia TNT 0.48 drivers (Detonator Drivers were used in the SSE Drivers Comparison)
  • DirectX 6.1
  • Quake 2 v3.20 w/ 3DNow! Support enabled when applicable

The benchmark suite consisted of the following applications:

  • Ziff Davis Winstone 98 under Windows 98
  • Ziff Davis Winstone 99 under Windows 98 & Windows NT4 SP4
  • Quake 2 v3.20 using demo1.dm2 and Brett "3 Fingers" Jacobs Crusher.dm2 demo
  • Naturally Speaking Professional Speech Recognition Software
  • Microsoft Netshow Encoder
  • Adobe Photoshop 5.02
  • Dispatch by Rage Software w/ SSE support

All Winstone tests were run at 1024 x 768 x 16 bit color, all gaming performance tests were run at 800 x 600 x 16 bit color. 3DNow! support was enabled when applicable.

For the in-depth gaming performance tests Brett "3 Fingers" Jacobs Crusher.dm2 demo was used to simulate the worst case scenario in terms of Quake 2 performance, the point at which your frame rate will rarely drop any further. In contrast, the demo1.dm2 demo was used to simulate the ideal situation in terms of Quake 2 performance, the average high point for your frame rate in normal play. The range covered by the two benchmarks can be interpreted as the range in which you can expect average frame rates during gameplay.

Index Windows 98 Performance

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