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• An End User's Question: How Many L2 Caches Does The Athlon Have?

  As it stands now, two different CPUs are available in the store with the XP 2800+ label, although there is no indication of an L2 cache from AMD. It is therefore not clear which CPU is being ordered. Only the oblong shape of the CPU die clues you in to the fact that you've got a Barton Athlon. The "FSB speed of 333 MHz" alone is not enough, especially considering the additional confusion AMD has created with the readjustment of the model numbering. Overclocking To 2500 MHz - How It Works 7 Basis for overclocking: board with socket 462 and a modern Athlon XP. We were forced to consider the subject of overclocking because AMD was not able to send us all three processors immediately for testing. Rather, the lab technicians had to unlock the only Athlon XP 3000+ in order to get the benchmark results for the "new" XP 2800+ and the XP 2500+. Just to recap and as way of explanation: in principle, all Athlon XP CPUs based on the Thoroughbred core (from 1700+ on) are unlocked when they leave the factory. You can tell this from the fact that the L1 bridges on the CPU are closed. By comparison, the Palomino and the old Thunderbird (also Duron's Spitfire and Morgan) had to be unlocked using the pencil method or the masking technique by closing the L1 bridges, as our own Uwe Scheffel first demonstrated. We have a downloadable MPEG video on the subject, Second THG Video: Unlocking The Athlon XP/MP . These tools are needed to unlock the translation table: tweezers and screwdriver.

• Overclocking In Detail: Athlon XP With 1866 MHz

  The fastest AMD processor to date is the Athlon XP 2000+ with 1666 MHz. The manufacturer delivered a CPU that was factory-fitted with a fixed multiplier, which we promptly unlocked according to our previous experience. You can read about this process in the article "Plastic Surgery: Releasing the Athlon XP To Hit 2000+ " and see it in the accompanying video "Second THG Video: Unlocking The Athlon XP/MP ." In order to attain the maximum increase in clock speed in an Athlon XP 2000+, it is necessary to lower the multiplier from 12.5 to 12.0. In the test, the Athlon ran stably up to a clock speed of 1866 MHz - at clock speeds even higher than this, it was no longer possible to conduct the benchmark tests. A clock speed of 1866 MHz corresponds to an Athlon XP 2300+. At this point, we should explain why we lowered the multiplier to 12.0: on the one hand, a clock rate of 1866 MHz cannot be achieved with an Athlon XP 1900+ that is factory-equipped with a multiplier of 2.0. On the other hand, it is necessary to set the FSB clock and memory clock as high as possible, so that the memory performance required for such a high CPU clock is available. Take the Quake III benchmark, for example, which gives you a visual comparison between the two multiplier settings (12.0 and 12.5) at an identical CPU clock speed. Processor Memory Clock CAS Latency Type of Memory Athlon XP 2300+ 155 MHz 2.5 DDR-SDRAM (DDR333, PC2700) Athlon XP 2200+ 150 MHz 2.5 DDR-SDRAM (DDR333, PC2700) Athlon XP 2100+ 144 MHz 2.0 DDR-SDRAM (DDR333, PC2700) Athlon XP 2000+ 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon XP 1900+ 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon XP 1800+ 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon XP 1700+ 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon XP 1600+ 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon XP 1500+ 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon 1400 133 MHz 2.0 DDR-SDRAM (DDR266, PC2100) Athlon 900 100 MHz 2.0 DDR-SDRAM (DDR266, PC2100) In the latest Athlon XP processors with the Palomino core, the maximum multiplier value is 12.5, which is technically limited. Every Socket 462 board has only four registers available for coding the CPU multiplier. Things will look different though, once AMD's Athlon XP 2200+ (Thoroughbred core) makes its debut at the CeBIT 2002 in March. With an FSB of 133 MHz, a board would have to offer a multiplier of 13.5 - AMD solves this problem with a translation table in the CPU. A further possibility is that the multiplier, as delivered with the board, would be fully ignored and that the CPU would dictate the settings. CPU Clock (MHz) Multipl. L1 FSB100 FSB133 X 1 2 3 4 5 500 667 5.0 open open open open open 550 733 5.5 open open open open open 600 800 6.0 open open open open open 650 867 6.5 open open open open open 700 933 7.0 open open open open open 750 1000 7.5 open open open open open 800 1067 8.0 open open open open open 850 1133 8.5 open open open open open 900 1200 9.0 open open open open open 950 1267 9.5 open open open open open 1000 1333 10.0 open open open open open 1050 1400 10.5 open open open open open 1100 1467 11.0 open open open open open 1150 1533 11.5 open open open open open 1200 1600 12.0 open open open open open 1250 1667 12.5 open open open open open Free closed closed closed closed closed CPU Clock (MHz) Multipl. L3 FSB100 FSB133 X 1 2 3 4 500 667 5.0 closed closed open open 550 733 5.5 open closed closed open 600 800 6.0 closed open open closed 650 867 6.5 open open closed closed 700 933 7.0 closed closed open open 750 1000 7.5 open closed closed open 800 1067 8.0 closed open open closed 850 1133 8.5 open open closed closed 900 1200 9.0 closed closed open open 950 1267 9.5 open closed closed open 1000 1333 10.0 closed open open closed 1050 1400 10.5 open open closed closed 1100 1467 11.0 closed closed open open 1150 1533 11.5 open closed closed open 1200 1600 12.0 closed open open closed 1250 1667 12.5 open open closed closed Free X X X X CPU Clock (MHz) Multipl. L4 FSB100 FSB133 X 1 2 3 4 500 667 5.0 open closed closed open 550 733 5.5 open closed closed open 600 800 6.0 open closed closed open 650 867 6.5 open closed closed open 700 933 7.0 closed open open closed 750 1000 7.5 closed open open closed 800 1067 8.0 closed open open closed 850 1133 8.5 closed open open closed 900 1200 9.0 open open closed closed 950 1267 9.5 open open closed closed 1000 1333 10.0 open open closed closed 1050 1400 10.5 open open closed closed 1100 1467 11.0 closed closed open open 1150 1533 11.5 closed closed open open 1200 1600 12.0 closed closed open open 1250 1667 12.5 closed closed open open Free X X X X CPU Voltage: 1.92 Volt For The Athlon Processor CPU Clock Clock Multiplier CPU Core Voltage Athlon XP 2300+ 1866 MHz 12 1,920 V Athlon XP 2200+ 1800 MHz 12 1,920 V Athlon XP 2100+ 1733 MHz 12 1,920 V Athlon XP 2000+ 1666 MHz 12.5 1,750 V Athlon XP 1900+ 1600 MHz 12 1,750 V Athlon XP 1800+ 1533 MHz 11.5 1,750 V Athlon XP 1700+ 1466 MHz 11 1,750 V Athlon XP 1600+ 1400 MHz 10.5 1,750 V Athlon XP 1500+ 1333 MHz 11 1,750 V Athlon 1400 1400 MHz 10.5 1,750 V Athlon 900 900 MHz 9 1,750 V An important condition for successful overclocking is the increase in CPU core voltage. AMD Athlon XP 2200+ processors from the factory work with 1.75 Volt. At such a setting, it is nearly impossible to increase the clock speed by a substantial amount. Extreme clock speeds of up to 1900 MHz are possible only if the CPU core voltage is increased to 1.90 Volt. Also, an increase in core voltage automatically causes an increase in the switching speed of the transistors, as well as a higher thermal power. The large amount of heat generated can be controlled by an efficient watercooling system. Otherwise, the processor will die a thermal death (see our video: Hot Spot - How Modern Processors Cope With Heat Emergencies ). Only a few boards with the VIA KT266A chipset offer a core voltage of more than 1.85 Volt. In the test, we use the Gigabyte GA-7VTXH, which allows a maximum of 1.92 Volt. Epox EP-8KHA+, a well-known and frequently used board, only allows a maximum of 1.85 Volt, which is not optimal for extreme overclocking. The only way to remedy this with the Epox is to modify the voltage regulator.

• AMD Athlon 64 X2 4600 (Windsor F2 Core, 2.4 GHz)

  The Athlon 64 X2, based on the Windsor core, is the backbone of AMD's socket AM2 offerings. All processors include a dual channel DDR2-800 memory controller and all command set extensions up to SSE3. This was also the first product generation where AMD introduced energy-efficient models, which run at a lower processor voltage and hence have a lower thermal design power (TDP). Compared to the Sempron we described on the previous page, this processor has two processing cores with 512 kB or 1 MB of L2 cache per core and TDP ratings of 89 W (up to 6000 and 3.0 GHz) or 125 W (6000 and 6400 at 3.2 GHz). We used a 2.4 GHz Athlon 64 X2 4600 processor with two 512 MB L2 caches. As there is no 90 nm processor that runs at a 2.3 GHz clock speed, we used the 2.4 GHz version (instead of using only 2.2 GHz). The 65 nm versions of the Athlon 64 X2 have similar performance ratings (3600 to 5400), but AMD adjusted the clock speeds due to slight performance differences when compared to the 90 nm Windsor cores. The 65 nm Brisbane is only available with 2x 512 kB L2 cache, while the fast Windsors all utilize 2x 1 MB second level cache. Hence you will see that many 65 nm Athlon 64 X2 processors come with odd clock speeds of 2.1, 2.3, 2.5 or 2.7 GHz, to make up for the performance impact of the smaller cache. When idle, the Athlon 64 X2 4600 will reduce its core clock speed to 1.0 GHz.