Intel Core 2 Quad Q8400S

The Intel Core 2 Quad Q8400S is a desktop processor from Intel's Core 2 Quad (Yorkfield) generation, released in 2009 and now end-of-life. It provides 4 physical cores and 4 threads with a fixed base clock of 2.67 GHz and no boost clock. Built on Intel's 45 nm process with 456 million transistors across a 2x 82 mm² dual-die package, it carries a 65W TDP. The cache hierarchy consists of 64 KB of L1 per core and a 4 MB shared L2, with no L3 cache. It occupies the 50th percentile among all CPUs in the database, placing it exactly at the median of the tracked performance distribution. The processor uses Intel Socket 775, supports dual-channel DDR1, DDR2, or DDR3 memory, and connects via PCIe Gen 2. ECC memory is not supported. Its part number is SLGT7.

How It Compares

The data lists no nearest rivals for the Q8400S. The nearestRivals field is empty, so a direct per-competitor comparison cannot be constructed from the available facts. What the data does provide is a percentile ranking: percentileVsAllCpus is 50, meaning the Q8400S sits at the exact midpoint of all CPUs tracked in the benchmark database. Half of all recorded processors fall above it and half below. This median placement indicates a part that is neither a performance leader nor a laggard; it occupies the center of the field. Without rival names or delta percentages, the only positional statement the data supports is this central standing.

The absence of rival data also means any claim about being ahead of or behind a specific competitor would be unsupported, so the analysis must rest on the architectural specifications and the single percentile figure. The empty rival list is itself informative: the database does not associate this processor with any close competitors, which may reflect its low-power niche within the Core 2 Quad lineup. The model name carries an "S" suffix, and the data confirms a 65W TDP, but the dataset does not explain the naming convention. The median placement implies that in mixed workloads, the processor lands between entry-level parts and high-end parts, though the data does not specify which workloads contribute to the ranking. Because the percentile is a single summary value, it does not reveal whether the processor is stronger in single-threaded or multi-threaded tasks.

Power and Thermals

The Q8400S is rated at a 65W TDP. That figure places it in a low-power class for a quad-core desktop processor. For cooling, a 65W part does not demand a large liquid cooler or a massive dual-tower air cooler; a capable air cooler with a modest heatsink is sufficient to manage the heat output. The 45 nm process node, with 456 million transistors on a 2x 82 mm² die, contributes to this efficiency. The die is split into two 82 mm² pieces, each containing two cores, yielding four cores total across the package. The 2x 82 mm² die configuration means the package contains two separate silicon dies, each with its own portion of the cache and cores, which is a design detail relevant to thermal distribution across the package.

The absence of a boost clock means the processor draws power at a steady rate corresponding to 2.67 GHz across all four cores; there is no transient high-frequency state that would spike thermals. For system builders, the thermal implication is straightforward: a standard desktop air cooler is adequate. The 65W rating is a thermal design power figure, not a measured maximum draw, but it guides cooler selection. The data shows no integrated graphics on the CPU itself, but notes "On certain motherboards (Chipset feature)" — meaning display output depends on the motherboard's chipset, not the processor. This affects system power draw: the motherboard chipset handles any integrated display output, while the CPU focuses solely on computation.

Benchmark Performance

The benchmark data for the Q8400S is absent. The benchmarks array is empty and the average benchmark score is 0. Consequently, there are no exact scores to compare against rivals, and no delta percentages can be computed. The only quantitative performance indicator is the 50th percentile ranking. This percentile is derived from the benchmark database's full CPU list, but without the underlying scores, the specific performance magnitude is unknown. The average benchmark score of 0 in the dataset may indicate that no runs were recorded, rather than a literal zero performance; the data does not clarify.

What can be analyzed is the architectural basis for performance. Four cores at 2.67 GHz with a 4 MB shared L2 cache and dual-channel memory form the compute backbone. The 2.67 GHz clock is the fixed operating point; there is no boost clock, so all workloads run at this frequency. The 4 MB shared L2 is a single pool accessible by all cores, which helps multi-threaded workloads that share data. The memory interface supports DDR1, DDR2, and DDR3 in dual-channel mode, but the data does not specify the supported speed grades for each memory type. In the absence of benchmark numbers, the processor's performance class must be inferred: it is a 4-core/4-thread part at a moderate clock speed, which positions it as a mid-range desktop CPU of its generation. The 50th percentile is consistent with this interpretation.

Who Should Consider It

The Q8400S is a desktop-market, end-of-life processor. Its 4 cores and 4 threads make it suitable for workloads that can use multiple threads simultaneously, such as office productivity suites, spreadsheet calculations, and light content creation. The fixed 2.67 GHz clock provides predictable performance for single-threaded tasks like web browsing and document editing. The dual-channel memory controller with DDR1, DDR2, and DDR3 support means it can be paired with a variety of memory types, though the specific memory speed is not specified in the data. With 4 threads, the processor can handle a typical office workload with background tasks, but it will not accelerate workloads designed for more than 4 threads.

The lack of integrated graphics on the CPU — with graphics being a chipset feature on certain motherboards — means a discrete graphics card is required for any display output unless the motherboard's chipset provides it. This processor is not suited for systems relying on CPU-integrated graphics. For a builder assembling a legacy Socket 775 system, the Q8400S offers a quad-core option with a 65W TDP, which is gentle on power supplies and cooling. It is end-of-life, so it is not a candidate for new high-end builds; rather, it fits retrofits or systems where the existing motherboard and memory are being reused. The 50th percentile ranking suggests it handles mainstream tasks adequately but does not excel at demanding workloads. Gamers seeking high frame rates would likely find the 2.67 GHz clock and Core 2 architecture limiting, but the data does not include gaming benchmarks to confirm this.

Platform and Compatibility

The Q8400S uses Intel Socket 775, a platform that is end-of-life. The processor supports DDR1, DDR2, and DDR3 memory in a dual-channel configuration. This broad memory compatibility is unusual and allows the processor to be installed on motherboards with different memory generations, though a given motherboard typically supports only one memory type. ECC memory is not supported. The PCIe interface is Gen 2, which dictates the bandwidth available for discrete graphics cards and other add-in cards.

The multiplier is locked, so overclocking via multiplier adjustment is not possible; any frequency increase would have to come from raising the base clock, which is not documented in the data. The integrated graphics situation is chipset-dependent: the data notes "On certain motherboards (Chipset feature)", meaning the processor itself does not contain a graphics unit, but some motherboards' chipsets provide display output. The part number is SLGT7. The processor was released in April 2009 and is now end-of-life, so the upgrade path is limited to other Socket 775 processors, but the data does not list which ones are compatible. The platform supports a dual-channel memory bus, and the PCIe Gen 2 standard is an older generation, which may constrain the performance of modern add-in cards. The Socket 775 platform is one of Intel's older desktop sockets, and the end-of-life status means new motherboard production has ceased.

Single-Thread vs Multi-Thread Behavior

The Q8400S has no boost clock, so its operating frequency is fixed at 2.67 GHz for both single-threaded and multi-threaded workloads. There is no dynamic frequency scaling that would give single-threaded tasks a higher clock. The processor has 4 cores and 4 threads, meaning there is no simultaneous multithreading; each core handles exactly one thread.

For single-threaded performance, the relevant factors are the 2.67 GHz clock and the Core 2 architecture's per-core efficiency. The L1 cache is 64 KB per core, which provides each core with its own low-latency cache. The L2 cache is 4 MB shared across all cores. The shared L2 cache is 4 MB total, not per core, so all four cores contend for the same cache capacity. In multi-threaded workloads, the shared L2 allows cores to exchange data without going through system memory, which is beneficial when threads operate on overlapping data. However, the lack of a boost clock means that when only one core is active, it still runs at 2.67 GHz — no single-core turbo is available. The dual-channel memory bus is shared by all cores, so memory bandwidth is a shared resource. The 4-thread limit caps the number of concurrent threads at 4; workloads with more than 4 threads will time-slice. This behavior is typical of a quad-core processor without hyper-threading. The 50th percentile ranking reflects this balanced but unexceptional capability in both single- and multi-threaded contexts.