With the release of the Barton a couple months ago, a lot of people were anticipating great things with the L2 cache getting a bump up to 512KB. If you've been paying attention, you'll know that the performance was not all that dramatic over their previous Thoroughbred cores. Fact is, both are the same CPU except for the added cache. Both are 166FSB parts (the latter TBreds that is), based on a 0.13 micron copper fab process. Many had hoped for the jump to 200FSB, but that is only available with the more recent 3200+.
The Barton 2500+
Packaging is the same as the Thoroughbred, which means it's based on the OPGA, or organic pin grid array, packaging technology. The benefit over ceramics (used in the Thunderbirds) is two-fold as it lowers the impedance and the cost of the CPU.
As you can see above, the markings are for a 2500+ CPU. Despite the bump in Performance Rating, this CPU has a lower clock speed than the 2400+. The 2500+ runs at 11x166 (1.83GHz), whereas the 2400+ runs at 15x133 (2GHz). Those numbers are rounded up, but basically, the 2400+ is about 170MHz faster.
So why did AMD feel fit to add 100PR? Well, as we've seen with the P4 Northwood, the extra 256KB of cache they added (to go up to 512KB) made quite a difference in performance. According to tests in their labs, AMD is making similar claims that the extra cache merits an increase in PR. We'll be sure to prove or disprove these claims in our tests.
To get an idea of how AMD determines it's performance rating, take a look at this graph...
Click to Enlarge
According to AMD, there are two factors in determining CPU performance, and that is the instructions per clock cycle (IPC) and clock speed, and I quote... "Until recently, the IPC of most computer processors was identical, so clock speed alone was used to determine performance capability. In current processors, however, IPC is different for competing processors, so performance is defined using both IPC and frequency. The end result is that frequency alone no longer determines performance. As a result of its QuantiSpeed architecture, the AMD Athlon XP processor has an optimum balance of IPC and frequency to achieve high levels of real world PC application performance."
Anyhow, I'm not going to bore you with all the technical details, since it's pretty much the same as the TBred 2400+ we've looked at earlier, so let's get right into the testing.
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