Architecturally, the Core I7 990x is no different to the processor it succeeds, the 980x. Both Gulftown processors boast 6 cores and 12 threads through hyper threading supporting a 12MB Cache, 4MB more than the quad core Bloomfield variants based on the 45nm Nehalem. The 12MB Cache is shared across all the cores but sticks to the 2MB per core rule (Westmere based Xeon quad core processors still retain the full 12MB L3 Cache despite the two disabled cores). The 990x simply ups the multiplier by one compared to its predecessor giving it a 133MHz boost in clock speed and Max Turbo Frequency. Like all other Extreme Edition processors, the multipliers are unlocked and the QPI speed is set to 6.4GT/s rather than 4.8GT/s. Thanks to the 32nm fabrication process, the actual processor package hasn’t changed in size and still retains a 130W thermal envelope. Quite impressively, Intel manages to pack 1.17 billion transistors in a smaller 239mm square die compared to Bloomfield which packed 731 million transistors on a 263mm square die. The on board memory controller remains unchanged supporting tri channel memory at the official speed of 1066MHz, although that is easily rectified using higher memory multipliers and overclocking.

The X58 chipset is very nicely suited to the Core i7 990x thanks to its 6.4GT/s QPI bus that communicates with the processor and memory channels. Unlike the recently released P67/Z68 chipsets for Sandy Bridge, X58 supports 36 PCIe lanes by default allowing for uncompromised SLI/CrossFire configurations at 2x16 lanes. This makes the Core i7 990x processor ideal for multi-GPU configurations.

Westmere also supports new AES instruction sets which come in benefit in some of our benchmarks compared to Nehalem. Let’s take a look at the comparison table.


Comparing the Intel Core i7 2600K, we see that on paper it doesn’t match up to the previous generation Core i7 990x with a lower default clock speed and fewer cores/threads. Sandy Bridge also goes back to dual channel memory since it is aimed at the mainstream market, thus representing the rightful successor to Lynnfield on the P55 chipset rather than Bloomfield/Gulftown on X58. What is important to note however is that the new architecture is superior clock for clock and finds itself in a lower 95W thermal envelope. Prices also favour Sandy Bridge which only the cheapest Bloomfield processors can match; currently the i7 960 at $294 with a clock speed of 3.2GHz. Architectural changes also give Sandy Bridge processors new instruction sets such as AVX, and an on-die GPU. Are the extra threads on the 990x enough for it to claim Intel’s flagship position? Let’s find out.