NVIDIA GeForce GT 555M vs NVIDIA GeForce GTX 580M Comparison

The GeForce GT 555M and GeForce GTX 580M are both end-of-life NVIDIA mobile GPUs from the GeForce 500M generation, but they occupy different positions in the lineup. The data shows a single benchmark result, Geekbench OpenCL, where the GT 555M scores 6493 and the GTX 580M scores 6389. This gives the GT 555M a 1.6% lead, a narrow margin that belies the substantial architectural differences between the two chips. The following analysis breaks down what these scores mean, where each GPU wins, and which device suits specific workloads based solely on the provided facts.

Where Each One Wins

The benchmark results indicate a clear, albeit narrow, victory for the GeForce GT 555M in the single available test. In the Geekbench OpenCL test, the GT 555M achieves a score of 6493, while the GTX 580M trails at 6389. This represents a delta of 1.6% in favor of the GT 555M. For compute-oriented tasks that mirror this OpenCL workload, the GT 555M holds the edge.

However, the data suggests that the GTX 580M's strengths lie elsewhere, specifically in memory bandwidth and raw pixel throughput. The GTX 580M has a memory bandwidth of 96.00 GB/s, which is over three times higher than the GT 555M's 28.80 GB/s. Its pixel rate is 9.920 GPixel/s, compared to 3.540 GPixel/s for the GT 555M. Similarly, the texture rate is 39.68 GTexel/s versus 14.16 GTexel/s. These figures point toward the GTX 580M being designed for fill-rate-limited scenarios, such as high-resolution gaming with heavy textures, even though the provided OpenCL benchmark does not reflect that advantage.

The GT 555M wins the compute benchmark, but the GTX 580M wins on memory and pixel processing capability. In the context of the nearest rivals, the GT 555M is 0.2% ahead of the NVIDIA Quadro M5000M (6481) and 0.3% ahead of the AMD Radeon Vega 10 Mobile (6476). The GTX 580M, conversely, sits exactly level with the NVIDIA GeForce GTX 460 SE (6389) and is 0.9% behind the AMD Radeon Pro WX 4100 (6330). This positions the GT 555M as a slightly stronger compute performer among its peers, while the GTX 580M is comparable to a mid-range desktop card from its era.

Architecture Differences

The two GPUs are built on different versions of the Fermi architecture, which explains their divergent design goals. The GT 555M uses the GF106 chip, based on the original Fermi architecture, manufactured on a 40 nm process at TSMC. It contains 1,170 million transistors on a die size of 238 mm², yielding a transistor density of 4.9M / mm². The GTX 580M, in contrast, uses the GF114 chip, based on the refined Fermi 2.0 architecture, also on a 40 nm process from TSMC. This chip packs 1,950 million transistors onto a larger 332 mm² die, with a higher density of 5.9M / mm².

The shader and memory hierarchies are fundamentally different. The GT 555M has 144 shading units, 24 texture mapping units (TMUs), and 16 render output units (ROPs). The GTX 580M more than doubles these counts: 384 shading units, 64 TMUs, and 32 ROPs. This explains the dramatic difference in compute throughput: the GTX 580M delivers 952.3 GFLOPS of FP32 performance, while the GT 555M manages only 339.8 GFLOPS. The memory subsystems are equally distinct. The GT 555M uses 1024 MB of DDR3 memory on a 128-bit bus, while the GTX 580M uses 2 GB of GDDR5 memory on a 256-bit bus. The effective memory clock speeds are 1800 Mbps for the GT 555M and 3000 Mbps for the GTX 580M, further widening the bandwidth gap.

Power and form factor also diverge sharply. The GT 555M has a thermal design power (TDP) of 35 W, making it suitable for thinner, less power-hungry laptops. The GTX 580M draws 100 W and is delivered as an MXM module with a bus interface of MXM-B (3.0), indicating a larger, more upgradeable chassis. Both share the same DirectX 12 (11_0) and OpenGL 4.6 API support, but the GTX 580M's higher resource counts give it a theoretical advantage in complex scenes that the benchmark data does not capture.

The Verdict

The data presents a nuanced picture. For users prioritizing raw compute in OpenCL workloads, the GeForce GT 555M is the better choice, as evidenced by its 1.6% higher benchmark score. Its lower TDP of 35 W also suggests it is a more efficient option for battery-constrained environments, though the numbers do not directly measure power efficiency.

For users who need high-resolution texture processing, the GeForce GTX 580M is the superior hardware, despite losing the single benchmark. Its 96.00 GB/s memory bandwidth, 9.920 GPixel/s pixel rate, and 2 GB of GDDR5 memory are all significantly higher than the GT 555M's 28.80 GB/s, 3.540 GPixel/s, and 1 GB of DDR3. The GTX 580M's 952.3 GFLOPS FP32 performance is also nearly three times that of the GT 555M.

Strictly from the provided data, the GT 555M is the winner in the compute test. However, the GTX 580M is the more capable graphics processor on paper for tasks that stress memory and fill rate. The benchmark's narrow margin suggests that the OpenCL test may not be sensitive to the GTX 580M's architectural strengths. Ultimately, the GT 555M wins on the sole measured metric, but the GTX 580M wins on specification-level capability. An analyst would note the GT 555M is the benchmark victor, while the GTX 580M offers superior theoretical performance for graphics-intensive applications.

FAQ

Q: Which GPU has the higher Geekbench OpenCL score?

A: The NVIDIA GeForce GT 555M scores 6493, which is 1.6% higher than the GeForce GTX 580M's score of 6389.

Q: How much memory bandwidth does each GPU provide?

A: The GTX 580M provides 96.00 GB/s of bandwidth, while the GT 555M provides 28.80 GB/s.

Q: What are the shading unit counts for these two GPUs?

A: The GT 555M has 144 shading units, while the GTX 580M has 384 shading units.

Q: Are both GPUs based on the same architecture?

A: No, the GT 555M uses the Fermi architecture (chip GF106), while the GTX 580M uses the Fermi 2.0 architecture (chip GF114).

Q: What is the TDP difference between the two?

A: The GT 555M has a TDP of 35 W, while the GTX 580M has a TDP of 100 W.

Q: Do both GPUs support the same DirectX version?

A: Yes, both support DirectX 12 (11_0) and OpenGL 4.6.

Head-to-Head Benchmarks

The only head-to-head benchmark available is Geekbench OpenCL. In this test, the GeForce GT 555M scores 6493, while the GeForce GTX 580M scores 6389. The winner is the GT 555M, with a delta of 1.6%. This is a surprising result given the GTX 580M's far larger resource pool.

The GTX 580M has 384 shading units versus 144, 64 TMUs versus 24, and 32 ROPs versus 16. Its FP32 compute is 952.3 GFLOPS versus 339.8 GFLOPS. Yet, the GT 555M still edges ahead in the OpenCL test. The most likely explanation, based on the data, lies in the memory clocks. The GT 555M's memory runs at 900 MHz (1800 Mbps effective), while the GTX 580M's memory runs at 750 MHz (3000 Mbps effective). The GTX 580M's bandwidth advantage comes from its wider 256-bit bus, not a faster clock. In a compute workload that may be latency-sensitive or poorly parallelized, the GT 555M's higher memory clock and lower TDP could contribute to its better relative performance.

The delta of 1.6% is small, though. The GT 555M is 0.2% ahead of its nearest rival, the Quadro M5000M (6481), and 0.3% ahead of the Radeon Vega 10 Mobile (6476). The GTX 580M is exactly tied with the GTX 460 SE (6389) and is 0.9% ahead of the Radeon Pro WX 4100 (6330). This shows both chips are in the same performance tier, despite the GTX 580M's superior specs. The benchmark result suggests that the GT 555M punches above its weight, while the GTX 580M underperforms relative to its hardware capabilities in this specific test.

Specification Differences

The specification sheets reveal stark contrasts between the two mobile GPUs. The GT 555M is a smaller, cooler chip: 238 mm² die size, 1,170 million transistors, and a 35 W TDP. The GTX 580M is a large, hot chip: 332 mm² die, 1,950 million transistors, and a 100 W TDP. Both are built by TSMC on a 40 nm process, but the GTX 580M has a higher transistor density at 5.9M / mm² versus 4.9M / mm².

Memory configurations are completely different. The GT 555M uses 1024 MB of DDR3 with a 128-bit bus, providing 28.80 GB/s. The GTX 580M uses 2 GB of GDDR5 with a 256-bit bus, providing 96.00 GB/s. The effective memory speeds are 1800 Mbps and 3000 Mbps, respectively. The GTX 580M's bandwidth is over three times higher.

Compute resources are heavily skewed toward the GTX 580M. It has 384 shading units, 64 TMUs, and 32 ROPs, versus 144, 24, and 16 for the GT 555M. This yields a pixel rate of 9.920 GPixel/s for the GTX 580M versus 3.540 GPixel/s, and a texture rate of 39.68 GTexel/s versus 14.16 GTexel/s. FP32 performance is 952.3 GFLOPS versus 339.8 GFLOPS, a 2.8x difference. The GTX 580M's form factor is an MXM module with an MXM-B (3.0) interface, while the GT 555M uses a standard PCIe 2.0 x16 interface. The GTX 580M has no power connectors listed, while the GT 555M's are unspecified. Both chips are end-of-life, with the GTX 580M releasing on 2011-06-27 and the GT 555M on 2011-07-01, both succeeding GeForce 400M and preceding GeForce 600M.