What is L2 cache?
Brought to you by The CPU Scorecard - Benchmarks & News, Prices & Reviews
The CPU Scorecard Home PageCPU FAQ List Benchmarks Comparisons Odds 'n' Ends Other Scores Overclocking Processors Shopping Upgrades
[ The CPU Scorecard > Processors > What is L2 cache? ] Previous

Latest CPU News
Compare CPU Speeds
Compare Computer Prices
Compare CPU Features

Intel CPU's
Transmeta CPU's

Ask the CPU Scorekeeper

Compare & Shop for
a NEW Computer
or Accessories
Buy or Sell
a USED Computer
or Accessories
Subscribe to our FREE newsletter for the latest CPU releases, reviews, and rankings!

Best multitasking CPU?
AMD Thunderbird serial number?
K6-2+ Not Just for Notebooks?
More Old CPU's?
CPU Temperature Limits?
AMD K6-2 400 vs Celeron 366?
Dual AMD CPU Support?
Athlon roadmap?
What about Dual Celerons?
Pentium-III vs K6-2?
Can I improve a K6-2 L2 cache?
Pentium-E? -B? -EB? What?
What is my CPU?
3D CPUs vs 3D graphics?
AMD K6 233 vs Cyrix MII 266?
K6-III FP performance?
Mac G3 450 score?
Is the AMD K6-2 3D?
Don't you like Intel processors?
Is a Celeron good enough?
Celeron vs Pentium?
AMD K6-2 vs Intel Celeron?
AMD K6 and Y2K?
Celeron vs P-II vs P-III?
Mobile P-II 333 vs Celeron 400?
What is L2 cache?


Dear CPU Scorekeeper

I would like to know more about the on-die L2 cache.
  1. Is it an alternative solution to the SRAM cache implementation?
  2. Which CPU's currently use the on-die L2 cache?
  3. Which CPUs currently use the SRAM cache?
  4. Are on-die caches cheaper to make than SRAM chips?
  5. As the fabrication process is reduced to 0.18 and smaller, will the on-die L2 cache be the future of caches on CPU's?
- - Se, October 1999

See the questionCPU Scorekeeper Responds

  1. YES.
  2. Intel's Celeron-A (300MHz and up) and mobile (not desktop) Pentium-II;
    AMD's K6-III.
  3. AMD's K6-2 & K6-III.
  4. NO.
  5. YES (IMHO).

There are currently three flavours of L2 cache employed in today's CPUs. SRAM (Static RAM) cache generally refers to the oldest of the three technologies, where the L2 cache is located on the system motherboard running at the speed of the Front Side Bus (FSB). An on-die L2 cache is a faster alternative to an SRAM cache, particularly as CPU clock speeds continue to increase.

To illustrate the performance impacts of the different types of L2 cache, take these CPUs as an example:

CPU (MHz) on-die L2 (MHz) BSB L2 (MHz) FSB L2 (MHz)
Celeron 300 ***** ***** *****       66
Intel Celeron 300 Performance
Celeron A 300 128 kb x 300 ***** *****       66
Intel Celeron 300A Performance
Celeron A 400 128 kb x 400 ***** *****       66
Intel Celeron 400 Performance
Pentium II 300 ***** 512 kb x 150 *****     100
Intel Pentium II 300 Performance
Pentium II 400 ***** 512 kb x 200 *****     100
Intel Pentium II 400 Performance
K6-2 300 ***** ***** 1024 kb x 100
AMD K6-2 300 Performance
K6-2 400 ***** ***** 1024 kb x 100
AMD K6-2 400 Performance

Intel's Celeron-A's demonstrate the newest implementation of L2 cache: built onto the same die as the CPU itself. Check the Celeron Stats page to see how the transistor count rises dramatically, as a result.

The Pentium-II uses a prior L2 technology, where the cache is built onto a dedicated Back Side Bus (BSB), between the FSB and the CPU. Although the BSB can run at the same speed as the CPU, cache memory capable of such speeds is much more expensive. Therefore, in the Pentium-II, the more economical half-speed cache is used (for a full-speed BSB, check out Intel's Xeon line).

AMD's K6-2 illustrates the oldest, on-board L2 cache design. Though the size of the cache is larger, its FSB speed limit shows its effect as CPU clock speeds increase.

The original Celeron-300, bereft of L2 cache, shows a significant performance penalty as a result. The L2-enabled Celeron-A at 300MHz is able to at least keep pace with a Pentium-II or K6-2 at the same clock speed.

At a processor speed of 400MHz, while its FSB runs at a pokey 66MHz, the Celeron-A still remains in the same performance league as both the Pentium II and the K6-2, mostly due to its newer on-die L2 cache.

Ask the CPU Scorekeeper


CPU Scorecard Quick Links
Compare CPU Speeds
The CPU Scorecard assumes no risk or liability for damage or loss due to the use of the information or advice provided here. All responses are based on the best available information at the time of writing. However, users of this information who wish to apply it to their computer situations do so at their own risk.
Top of page...CPU FAQ List Benchmarks Comparisons Odds 'n' Ends Other Scores Overclocking Processors Shopping Upgrades

We appreciate your feedback!

Copyright 1998-2003
MTekComputer Consulting Ltd
All rights reserved