AMD Athlon 1GHz, 950MHz, 900MHz

·        22 million transistor AMD K75 0.18-micron core

·        900MHz clock speed – 9.0x clock multiplier

·        128KB on-die L1 cache running at core speed

·        512KB external on-card L2 cache running at 1/3 core speed (300MHz)

·        242-pin Slot-A EV6 CPU Interface running at 100MHz DDR (effectively 200MHz)

·        1.80v core voltage

In order to reach 900MHz, AMD made use of two tricks that overclockers are quite familiar with.  For starters, they increased the core voltage of the CPU to 1.80v which is an increase from the 1.70v of the 850 and the 1.60v of all other Athlon processors.  By increasing the core voltage to 1.80v, they can effectively increase the yield on their CPUs, and since 1.80v is within the Athlon’s range of tolerance, all should be fine. 

The second trick they used to keep the clock speed up there is to change the L2 cache multiplier once again, this time taking it down to 1/3 of the core clock speed.  The last time AMD lowered the multiplier was with the Athlon 750 as they got rid of the 1/2 L2 cache multiplier and replaced it with a 2/5 setting to help keep the L2 cache speed below 350MHz.  Why 350MHz?  It is quite costly and not worth the price/performance ratio to pursue off-die L2 cache that runs that high. 

This time around the Athlon takes on a 1/3 multiplier which, in the case of the Athlon 900, keeps the L2 cache running at 300MHz, equal to the speed of the L2 cache on the Athlon 600 which used a 1/2 multiplier.  The Athlon 900 is obviously faster than the original 600 because of the increase in clock speed; the main issue with dropping the L2 cache speed is that the improvement gained by increasing the clock speed isn’t as great as it would be had the CPU featured a full speed L2 cache. 

·        22 million transistor AMD K75 0.18-micron core

·        950MHz clock speed – 9.5x clock multiplier

·        128KB on-die L1 cache running at core speed

·        512KB external on-card L2 cache running at 1/3 core speed (316.67MHz)

·        242-pin Slot-A EV6 CPU Interface running at 100MHz DDR (effectively 200MHz)

·        1.80v core voltage

The 950 features the same 1.80v core voltage setting and 1/3 L2 cache multiplier as the 900.  The L2 cache in this case operates about 6% faster than on the Athlon 900 and should, in addition to the higher clock speed, help performance a little bit. 

·        22 million transistor AMD K75 0.18-micron core

·        1000MHz/1GHz clock speed – 10.0x clock multiplier

·        128KB on-die L1 cache running at core speed

·        512KB external on-card L2 cache running at 1/3 core speed (333.33MHz)

·        242-pin Slot-A EV6 CPU Interface running at 100MHz DDR (effectively 200MHz)

·        1.80v core voltage

The Magnolia is the major release here.  While it is not much different than the previous two CPUs, the simple fact that it runs at 1GHz is what makes it so special.  Just three months ago we had to cool the Athlon down to –40C in order to get it to run at 1GHz, and now we have an air cooled part running at just that frequency.  That alone is impressive to say the least.

The 1GHz Athlon also suffers from the crippling of the 1/3 L2 cache multiplier that keeps its L2 cache running at about 333MHz which is just slightly slower than the 850’s 340MHz L2. 

So to those that may have been expecting otherwise, the 900, 950 and 1GHz Athlons are not based on the new Thunderbird core we have been waiting for and still use an external L2 cache.