Xeon 6520p vs. Xeon 6521p

[dominiaz]

I’m trying to figure out which CPU is faster: the Intel Xeon 6520p vs. 6521p. They’re priced almost identically, and I don’t care about the 136 PCIe lanes.

What really matters to me is single-thread performance, but the more I read about them, the more confused I get. The CPU will run under Proxmox and will be attached to a Mellanox 100/200 G shared NVMe storage array capable of about 3 million IOPS.

According to Intel’s own datasheets, the 6521p should be the faster chip. However, early PassMark results show weaker single-thread scores for the 6521p and stronger ones for the 6520p.

Xeon 6520p - Single Thread Rating 3349 (passmark)
Xeon 6521p - Single Thread Rating 2829 (passmark)

Lenovo’s SPEC CPU benchmarks also show the 6520p significantly outpacing the 6521p:

https://lenovopress.lenovo.com/lp1262-intel-xeon-scalable-processor-comparison

Meanwhile, HPE publishes completely different SPEC CPU2017 results for these two models:

https://spec.org/cpu2017/results/res2025q2/cpu2017-20250406-47364.pdf

https://spec.org/cpu2017/results/res2025q2/cpu2017-20250406-47330.pd

Can anyone help me decide which one to pick? Thanks in advance!

[Sazirah]

Hi dominiaz,

Greetings.

Thank you for posting in Intel Community Forum.

Both CPUs Intel Xeon 6520P Processor and Intel Xeon 6521P Processor are based on the Granite Rapids-SP architecture, built on a 5nm process, carrying each own edges and advantages. 

You may refer to the product comparisons for each CPUs here: https://www.intel.com/content/www/us/en/products/compare.html?productIds=242640,242634

The Xeon 6521P has a higher TDP (225W vs 210W), for heavier multi-threaded workloads.

Per CPU specs, if the workloads are latency-sensitive or rely on fast single-thread execution the Xeon 6520P is the better choice. However, all will be according to your usage preference as both CPUs are great with their own advantages.

Hope this clarifies.

Regards,

Sazzy_Intel

Intel Customer Support Technician

[Sazirah]

Hi dominiaz,

Greetings.

This is related to your enquiries above, I would like to check if the issue has resolved?

If you have any questions or clarifications, please let me know.

Regards,

Sazzy

Intel Customer Support Technician

[Sazirah]

Hi dominiaz,

Greetings.

This is regarding your enquiries above. Since we have not seen an update, if you need any additional information, please submit a new question as this thread will no longer be monitored.

Best Regards,

Sazzy_Intel

Intel Customer Support Technician