Intel Core i7-3820QM vs Intel Xeon D-1521 Comparison

The Intel Xeon D-1521 and Intel Core i7-3820QM are near-perfect statistical twins in synthetic workloads, separated by a razor-thin 0.1% in average benchmark score (1367 vs 1366). Despite this, their underlying designs could not be more different, with the Xeon targeting server racks and the i7 built for laptops. The data shows a consistent, albeit tiny, edge for the i7-3820QM across nearly every Cinebench test, yet the Xeon D-1521 holds its own in a single test and offers entirely different platform features that make it the right choice for a specific use case.

Head-to-Head Benchmarks

The most striking finding is how close these two processors are in raw compute performance. In the Cinebench R23 multi-core test, the i7-3820QM scores 4777 against the Xeon D-1521’s 4728, a difference of just 1%. This pattern repeats in Cinebench R20 multi-core (2006 vs 1985, a 1% delta) and Cinebench R15 multi-core (481 vs 476, also a 1% delta). The i7-3820QM wins all three multi-core tests, but the margins are so small that they would be imperceptible in real-world use. A 1% lead in a rendering benchmark is effectively a tie; it suggests both CPUs are saturating their 4-core/8-thread configurations similarly.

Single-core results tell the same story. In Cinebench R23 single-core, the i7-3820QM posts 674 versus the Xeon’s 667 (a 1% delta). The R20 single-core test shows the i7 ahead at 283 vs 280, a 1.1% margin. The only test where the Xeon D-1521 wins outright is Cinebench R15 single-core, where both score exactly 67, a 0% delta that the database awards to the Xeon. This is a statistical dead heat, not a performance victory. The i7-3820QM’s higher boost clock (3.70 GHz vs 2.70 GHz) should give it a clear advantage in lightly threaded tasks, but the benchmark data shows that advantage is negligible, at least in this older Cinebench version.

Looking at the broader picture, both CPUs land in the 36th percentile of all CPUs tracked, meaning they sit at the same performance tier. The i7-3820QM’s nearest rival list includes the Xeon D-1521 with a delta of -0.1%, confirming the two are effectively interchangeable in raw throughput. The Xeon’s nearest rivals include the Intel Xeon E5-1410 v2 (delta -0.1%) and AMD Opteron 6376 (delta -0.2%), placing it in the same mid-range server/workstation bracket. In short, if you are choosing based purely on Cinebench scores, you are flipping a coin.

FAQ

Q: Which CPU has the higher average benchmark score?

A: The Intel Xeon D-1521 has an average benchmark score of 1367, while the Intel Core i7-3820QM scores 1366. The difference is 0.1% in favor of the Xeon, which is within the margin of error for these tests.

Q: Does the Core i7-3820QM beat the Xeon in every multi-core test?

A: Yes. The i7-3820QM wins Cinebench R15 multi-core (481 vs 476), R20 multi-core (2006 vs 1985), and R23 multi-core (4777 vs 4728). Each win is by a 1% margin.

Q: Is there any test where the Xeon D-1521 wins?

A: The Xeon D-1521 is marked as the winner in Cinebench R15 single-core, but only because both CPUs scored exactly 67, resulting in a 0% delta. It does not win any test by a measurable margin.

Q: What is the difference in boost clock speeds?

A: The Core i7-3820QM boosts to 3.70 GHz, while the Xeon D-1521 boosts to 2.70 GHz. Despite this 1.0 GHz difference, the single-core benchmark scores are nearly identical.

Q: Do both CPUs support ECC memory?

A: No. The Xeon D-1521 supports ECC memory, while the Core i7-3820QM does not. The Xeon also supports both DDR3 and DDR4 memory, whereas the i7’s memory support is not specified in the data.

Q: Which CPU has a higher transistor count?

A: The Xeon D-1521 has 3,200 million transistors on a 246 mm² die, while the Core i7-3820QM has 1,400 million transistors on a 160 mm² die. The Xeon’s transistor count is more than double.

Architecture Differences

The architectural gap between these two parts is vast, even though their benchmark scores are not. The Xeon D-1521 is built on the Broadwell architecture using a 14 nm process node, while the Core i7-3820QM uses the older Ivy Bridge architecture on a 22 nm node. This process advantage allows the Xeon to pack 3,200 million transistors into a 246 mm² die, compared to the i7’s 1,400 million transistors on a 160 mm² die. Despite the Xeon’s higher transistor count and smaller process, it does not translate into higher clock speeds; the i7’s 3.70 GHz boost is a full 1.0 GHz higher than the Xeon’s 2.70 GHz.

Cache configurations also differ fundamentally. The Xeon D-1521 has 1.5 MB of L3 cache per core, which totals 6 MB across four cores. The Core i7-3820QM has 8 MB of shared L3 cache for all cores. The L1 and L2 caches are identical (64 KB and 256 KB per core, respectively), but the shared vs per-core L3 design reflects their different target workloads. The Xeon’s per-core allocation is typical for server parts that may run virtualized or isolated workloads, while the i7’s shared pool is better for consumer applications that benefit from a large unified cache.

The most significant feature divergence is ECC memory support. The Xeon D-1521 supports ECC and offers DDR3 and DDR4 memory support, making it suitable for error-correcting server environments. The Core i7-3820QM lacks ECC entirely and has no memory type specified in the data. Additionally, the Xeon includes 24 PCIe Gen 3 lanes (CPU only), while the i7 has no PCIe specification listed. The i7 does include integrated graphics (Intel HD 4000), whereas the Xeon has none. This is a clear split: the Xeon is a headless server chip, and the i7 is a mobile processor with graphics built in.

Specification Differences

• Base Clock: The Core i7-3820QM runs at 2.70 GHz, while the Xeon D-1521 runs at 2.40 GHz.
• Boost Clock: The Core i7-3820QM boosts to 3.70 GHz, compared to the Xeon’s 2.70 GHz.
• Process Node: The Xeon D-1521 uses 14 nm, while the Core i7-3820QM uses 22 nm.
• Transistors: The Xeon D-1521 has 3,200 million, the Core i7-3820QM has 1,400 million.
• Die Size: The Xeon D-1521 measures 246 mm², the Core i7-3820QM measures 160 mm².
• L3 Cache: The Xeon D-1521 has 1.5 MB per core, the Core i7-3820QM has 8 MB shared.
• Socket: The Xeon D-1521 uses Intel BGA 1667, the Core i7-3820QM uses Intel BGA 1224.
• Memory Support: The Xeon D-1521 supports DDR3 and DDR4; the Core i7-3820QM has no memory type listed.
• ECC Memory: The Xeon D-1521 supports it; the Core i7-3820QM does not.
• PCIe: The Xeon D-1521 has Gen 3, 24 lanes (CPU only); the Core i7-3820QM has no PCIe data.
• Integrated Graphics: The Xeon D-1521 has none; the Core i7-3820QM has Intel HD 4000.
• Market Segment: The Xeon D-1521 is Server/Workstation; the Core i7-3820QM is Mobile.
• Release Date: The Xeon D-1521 launched on 2015-10-31; the Core i7-3820QM launched on 2012-04-28.
• Launch MSRP: The Xeon D-1521 has a launch MSRP of $199; the Core i7-3820QM has no listed MSRP.

Where Each One Wins

The Core i7-3820QM wins in raw benchmark performance, taking 5 of the 6 head-to-head tests. Its victory margins are consistent but tiny, ranging from 1% to 1.1%. If you are comparing these solely on Cinebench scores, the i7-3820QM is the faster chip in multi-core and most single-core tests. It also offers integrated graphics, which is a practical win for any system that needs a display output without a discrete GPU. Its higher boost clock of 3.70 GHz gives it a theoretical edge in bursty, single-threaded tasks, even if the benchmarks do not show a large real-world gap.

The Xeon D-1521 wins where the benchmarks do not measure: platform features. It is the only one of the two with ECC memory support, making it the correct choice for file servers, NAS builds, or any workload where data integrity is non-negotiable. Its support for both DDR3 and DDR4 memory gives builders more flexibility in choosing RAM, and its 24 PCIe Gen 3 lanes (CPU only) allow for more direct expansion options. The Xeon is also the newer part, released in late 2015 versus the i7’s early 2012 launch, meaning it is built on a more modern 14 nm process with more than double the transistor count. For a dedicated server platform that runs 24/7, the Xeon’s active production status and ECC support outweigh its 1% benchmark deficit.

The Verdict

The data presents a clear choice based on use case, not performance. If you are building a mobile workstation or a compact system where integrated graphics and a higher boost clock are useful, the Core i7-3820QM is the pick. It wins the majority of benchmark tests, albeit by margins under 1.1%, and provides a complete package with Intel HD 4000 graphics. Its 3.70 GHz boost clock is significantly higher than the Xeon’s 2.70 GHz, which may help in older or poorly threaded software even if Cinebench does not show it.

If you are building a server or workstation where stability and error correction matter, the Xeon D-1521 is the only rational choice. ECC memory support is a hard requirement for many server workloads, and the Xeon’s dual DDR3/DDR4 support and 24 PCIe Gen 3 lanes offer more platform flexibility. The 1% performance deficit in Cinebench is irrelevant when the alternative is risking memory corruption in a 24/7 environment. Its $199 launch MSRP is a data point, but the real value is in the server-grade features. In short: pick the i7 for a fast laptop, pick the Xeon for a reliable server. They are equals in speed, but not in purpose.