Celeron 3855U vs Core 2 Duo T9900

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.

Celeron 3855U vs Core 2 Duo T9900 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.

Celeron 3855U vs Core 2 Duo T9900: Pros, Cons & Final Verdict

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

Celeron 3855U

2015

Why buy it

✅Draws 15W instead of 35W, a 20W reduction.
✅100+% more PCIe lanes (10 vs 0) for storage and expansion-heavy builds.
✅Integrated graphics onboard with Intel HD Graphics 510, while Core 2 Duo T9900 needs a discrete GPU.

Trade-offs

❌Smaller total L3 cache (2 MB vs 6 MB).

Core 2 Duo T9900

2009

Why buy it

✅+200% larger total L3 cache (6 MB vs 2 MB).

Trade-offs

❌Lower PassMark (1,204 vs 1,215).
❌133.3% higher power demand at 35W vs 15W.
❌No integrated graphics, while Celeron 3855U can still boot and troubleshoot without a discrete GPU.

Quick Answers

So, is Celeron 3855U better than Core 2 Duo T9900?

Yes. Celeron 3855U is the better all-around CPU here. It gives you a 0.1% average FPS lead across 48 shared CPU game tests in our data, 0.9% better PassMark, and the stronger long-term platform, which is enough to make it the stronger overall pick.

Which one is better for gaming?

If gaming is the priority, Celeron 3855U is the better pick. According to our tests, it delivers 0.1% more average FPS across 48 shared CPU game tests.

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

For streaming, content creation, and heavier multitasking, Celeron 3855U is the stronger fit. You are getting 0.9% better PassMark, backed by 2 cores and 2 threads.

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

Celeron 3855U still makes the most sense overall. Celeron 3855U comes in at an unclear MSRP at unclear MSRP versus unclear MSRP, and it still gives you a 0.1% average FPS lead across 48 shared CPU game tests in our data.

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

Celeron 3855U makes more sense long term for 2026 and beyond. You are getting a newer CPU generation (2015 vs 2009) and more multi-core headroom with 2 cores / 2 threads instead of 2/2. That extra compute headroom is more likely to matter as games, background tasks, and creator workloads get heavier.

Celeron 3855U vs Core 2 Duo T9900 Technical Specifications

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

Celeron 3855U

The Celeron 3855U is manufactured by Intel. It was released in 15 August 2015 (10 years ago). It is based on the Skylake (2015−2016) architecture. It features 2 cores and 2 threads. Base frequency is 1.6 GHz, with boost up to 1.6 GHz. L3 cache: 2 MB. L2 cache: 512 kB. Built on 14 nm process technology. Socket: BGA1356. Thermal design power (TDP): 15 Watt. Memory support: DDR4-1866/2133, LPDDR3-1600/1866, DDR3L-1333/1600. Passmark benchmark score: 1,215 points. Launch price was $107.

Core 2 Duo T9900

The Core 2 Duo T9900 is manufactured by Intel. It was released in 2 June 2009 (16 years ago). It is based on the Penryn (2008−2011) architecture. It features 2 cores and 2 threads. Base frequency is 3.06 GHz, with boost up to 0.07 GHz. L3 cache: 6 MB L2 Cache. L2 cache: 6 MB (total). Built on 45 nm process technology. Socket: PGA478. Thermal design power (TDP): 35 Watt. Memory support: DDR2, DDR3. Passmark benchmark score: 1,204 points. Launch price was $530.

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Processing Power

Both the Celeron 3855U and Core 2 Duo T9900 share an identical 2-core/2-thread configuration. Boost clocks reach 1.6 GHz on the Celeron 3855U versus 0.07 GHz on the Core 2 Duo T9900 — a 183.2% clock advantage for the Celeron 3855U (base: 1.6 GHz vs 3.06 GHz). The Celeron 3855U uses the Skylake (2015−2016) architecture (14 nm), while the Core 2 Duo T9900 uses Penryn (2008−2011) (45 nm). In PassMark, the Celeron 3855U scores 1,215 against the Core 2 Duo T9900's 1,204 — a 0.9% lead for the Celeron 3855U. L3 cache: 2 MB on the Celeron 3855U vs 6 MB L2 Cache on the Core 2 Duo T9900.

Feature	Celeron 3855U	Core 2 Duo T9900
Cores / Threads	2 / 2	2 / 2
Boost Clock	1.6 GHz+2186%	0.07 GHz
Base Clock	1.6 GHz	3.06 GHz+91%
L3 Cache	2 MB	6 MB L2 Cache+200%
L2 Cache	512 kB	6 MB (total)+1100%
Process	14 nm-69%	45 nm
Architecture	Skylake (2015−2016)	Penryn (2008−2011)
PassMark	1,215	1,204
Geekbench 6 Single	361	—
Geekbench 6 Multi	632	—

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Memory & Platform

The Celeron 3855U uses the BGA1356 socket (PCIe 3.0), while the Core 2 Duo T9900 uses PGA478 (PCIe 1.1) — making them incompatible on the same motherboard.

Feature	Celeron 3855U	Core 2 Duo T9900
Socket	BGA1356	PGA478
PCIe Generation	PCIe 3.0+173%	PCIe 1.1
Max RAM Speed	DDR4 2133 MHz	—
Max RAM Capacity	32 GB	—
RAM Channels	2	—
ECC Support	No	—
PCIe Lanes	10	—

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Advanced Features

Virtualization: true (Celeron 3855U) / not specified (Core 2 Duo T9900). The Celeron 3855U includes integrated graphics (Intel HD Graphics 510), while the Core 2 Duo T9900 requires a dedicated GPU. Primary use case: Celeron 3855U targets Budget. Direct competitor: Celeron 3855U rivals Pentium 3825U.