Closer Look at Core 2 Quad Q9300
We have already discussed new quad-core Penryn processors in detail in our Core 2 Extreme QX9650 Review. All in all, our today’s hero, Core 2 Quad Q9300, doesn’t differ from the QX9650 from architectural standpoint. It is built with two dual-core semiconductor Wolfdale dies stuffed into a single processor packaging. These dies communicate with one another via the front side bus and system memory, just like the dies of the quad-core Kentsfield processors.
The clock frequency of Core 2 Quad Q9300 processor, the youngest Yorkfield CPU, is 2.5GHz, the front side bus frequency is 333MHz (1333MHz quad-pumped). Just like Wolfdale processors, Yorkfield supports fractional multipliers with 0.5x increment, which explains where its unusual clock frequency comes from: it is obtained with a 7.5x multiplier.
Compared with other members of Core 2 Quad Q9000 processor family, the solution reviewed today boasts one distinguishing feature: smaller L2 cache. Instead of the 6MB for each pair of cores we would expect it to have, Core 2 Quad Q9300 has the total of 6MB of L2 cache memory. In other words, each of the dual-core dies within this processor features an L2 cache half the size: only 3MB.
Diagnostic utilities, such as CPU-Z, for instance, detect this peculiarity flawlessly:
The screenshots above reveal all the major characteristics of our today’s processor. Note that the CPU we tested has C0 core stepping that is also used in dual-core Core 2 Duo E8000. Nevertheless, this core stepping will not be used in mass production, it will be replaced with C1 (or M1) core stepping, which will be free from bugs that delayed mass shipments of Core 2 Quad Q9000 CPUs. However, you shouldn’t expect the new core stepping to bring in any significant improvements. According to Intel, there will be nothing new in its electrical, thermal or mechanical characteristics.
Here I would only like to say that the official price of Core 2 Quad Q9300 is set at $266. This way, the new Core 2 Quad Q9300 with 45nm cores will come to replace Core 2 Quad Q6600, so it makes perfect sense to compare them side by side:
Besides micro-architectural improvements such as new SSE4.1 instructions support and introduction of faster Fast Radix-16 Divider and Super Shuffle Engine functional units, Core 2 Quad Q9300 is superior to its predecessor in clock frequency and bus speed. However, its L2 cache memory is smaller than that of Core 2 Quad Q6600.
How critical is that for the performance? Let’s find out!