Atom Z520 vs Pentium III 1266S

PassMark CPU Mark evaluates processor speed through complex mathematical computations. It provides a reliable metric to compare multi-core performance, where higher scores indicate faster processing for multitasking, gaming, and heavy workloads.

Atom Z520 vs Pentium III 1266S FPS Benchmarks

Predicted gaming performance across popular games. Tested paired with GeForce RTX 5090 to isolate CPU performance.

Search any supported game below to compare 1080p FPS for both components.

Atom Z520 vs Pentium III 1266S: Pros, Cons & Final Verdict

See where each CPU makes more sense in practice: gaming, heavier work, platform cost, power draw, and upgrade path.

Atom Z520

2008

Why buy it

✅+2.4% higher PassMark.
✅Draws 2W instead of 30W, a 28W reduction.

Trade-offs

❌Fewer obvious downsides in this matchup outside of normal market pricing swings.

Pentium III 1266S

2001

Why buy it

Trade-offs

❌Lower PassMark (210 vs 215).
❌Launch MSRP is still $369 MSRP, while Atom Z520 mostly shows up through inconsistent older-market listings.
❌1400% higher power demand at 30W vs 2W.

Quick Answers

So, is Atom Z520 better than Pentium III 1266S?

It depends on what you want from the system. For gaming, Pentium III 1266S is ahead with 4133.3% higher max boost clock. For rendering, compiling, streaming, and heavier multitasking, Atom Z520 pulls ahead with 2.4% better PassMark.

Which one is better for streaming, content creation, and heavy multitasking?

For streaming, content creation, and heavier multitasking, Atom Z520 is the stronger fit. You are getting 2.4% better PassMark, backed by 1 cores and 2 threads.

Which one is the smarter buy today, not just the cheaper CPU?

Atom Z520 is still the much better call for a fresh build. Atom Z520 comes in at an unclear MSRP at unclear MSRP versus $369 MSRP, and it still gives you 2.4% better PassMark. Pentium III 1266S only looks stronger on raw value math because it is extremely cheap, but that usually means used-market pricing on an obsolete 2001 platform. Even with 100.0% better value on paper (0.6 vs 0.0 PassMark/$), it really only makes sense as a cheap stopgap or a niche existing-platform option for someone already on PGA370.

Which one is more future-proof for 2026 and beyond?

Atom Z520 makes more sense long term for 2026 and beyond. You are getting a newer CPU generation (2008 vs 2001) and more multi-core headroom with 1 cores / 2 threads instead of 1/1. That extra compute headroom is more likely to matter as games, background tasks, and creator workloads get heavier.

Atom Z520 vs Pentium III 1266S Technical Specifications

Side-by-side specs, architecture details, clocks, memory, power, and platform differences.

Atom Z520

The Atom Z520 is manufactured by Intel. It was released in 2 April 2008 (17 years ago). It is based on the Silverthorne (2008−2010) architecture. It features 1 cores and 2 threads. Base frequency is 1.33 GHz, with boost up to 0.03 GHz. L3 cache: 0 kB. L2 cache: 512 kB. Built on 45 nm process technology. Socket: PBGA441. Thermal design power (TDP): 2 Watt. Passmark benchmark score: 215 points. Launch price was $65.

Pentium III 1266S

The Pentium III 1266S is manufactured by Intel. It was released in 2007-01-01. It is based on the Tualatin (2000−2002) architecture. It features 1 cores and 1 threads. Max frequency: 1.27 GHz. L3 cache: 0 kB. L2 cache: 512 kB. Built on 130 nm process technology. Socket: PGA370. Thermal design power (TDP): 30 Watt. Passmark benchmark score: 210 points. Launch price was $69.

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Processing Power

The Atom Z520 packs 1 cores / 2 threads, matching the Pentium III 1266S's 1 cores. Boost clocks reach 0.03 GHz on the Atom Z520 versus 1.27 GHz on the Pentium III 1266S — a 190.8% clock advantage for the Pentium III 1266S. The Atom Z520 uses the Silverthorne (2008−2010) architecture (45 nm), while the Pentium III 1266S uses Tualatin (2000−2002) (130 nm). In PassMark, the Atom Z520 scores 215 against the Pentium III 1266S's 210 — a 2.4% lead for the Atom Z520. Both processors carry 0 kB of L3 cache.

Feature	Atom Z520	Pentium III 1266S
Cores / Threads	1 / 2	1 / 1
Boost Clock	0.03 GHz	1.27 GHz+4133%
Base Clock	1.33 GHz	—
L3 Cache	0 kB	0 kB
L2 Cache	512 kB	512 kB
Process	45 nm-65%	130 nm
Architecture	Silverthorne (2008−2010)	Tualatin (2000−2002)
PassMark	215+2%	210

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Memory & Platform

The Atom Z520 uses the PBGA441 socket (PCIe 2.0), while the Pentium III 1266S uses PGA370 (PCIe 1.1) — making them incompatible on the same motherboard.