# How Does the RTX 5090 Perform Without PCIe 5.0 x16? Initial Benchmarks Show Slight Decrease
Earlier this month, Nvidia introduced its eagerly awaited RTX 5090 graphics card, along with other models in the Blackwell GPU family. These graphics cards are the first to utilize the advanced PCI Express 5.0 x16 interface, which promises exceptional bandwidth and performance for gaming and professional tasks. However, many motherboards on the market do not support PCIe 5.0, leading users to question: how much performance is sacrificed when connecting the RTX 5090 through PCIe 4.0 or even PCIe 3.0?
To find answers, **TechPowerUp** conducted a comprehensive range of benchmarks to assess the RTX 5090’s performance under various PCIe conditions. The findings are encouraging for users without the latest technology: the performance reduction is surprisingly minimal, even when older PCIe versions are used.
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## **RTX 5090 on PCIe 4.0: Minor Performance Decrease**
TechPowerUp’s assessments showed that the RTX 5090 functions remarkably well even when linked through PCIe 4.0, with a mere negligible performance dip compared to PCIe 5.0. The benchmarks were performed on a high-performance setup featuring an **AMD Ryzen 7 9800X3D processor**, an **X870E motherboard**, and **32 GB of RAM** to mitigate possible bottlenecks unrelated to the PCIe configuration.
### Key Observations:
1. **PCIe 5.0 x16 vs. PCIe 4.0 x16**:
– The average performance reduction when switching from PCIe 5.0 x16 to PCIe 4.0 x16 was only **1%**.
– This slight variation was consistent across different resolutions, including Full HD (1080p), 1440p, and 4K.
2. **PCIe 4.0 x8 or PCIe 3.0 x16**:
– A somewhat larger performance decline of about **4%** was noted when the bandwidth was reduced, as with PCIe 4.0 x8 or PCIe 3.0 x16.
3. **PCIe 3.0 x8**:
– The most noticeable drop observed with PCIe 3.0 x8, where the performance decreased by approximately **10%**, depending on the resolution and game in use.
These findings indicate that the RTX 5090 is remarkably adept at maximizing available bandwidth, with the PCIe interface only becoming a limiting element in extreme cases.
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## **When Does PCIe Bandwidth Become Limiting?**
Although the RTX 5090’s performance remains predominantly stable in most gaming and productivity contexts, there are specific instances where PCIe bandwidth may become constraining. For example:
– **High VRAM Consumption**:
The RTX 5090 is equipped with a substantial **32 GB of GDDR7 memory**, adequate for most applications. However, if a game or application surpasses this VRAM capacity, the GPU must transfer data to system memory through the PCIe interface. In such situations, reduced PCIe bandwidth may result in noticeable performance drops.
– **Memory-Heavy Tasks**:
Content creation activities, such as RAW media processing or 3D rendering, can place more strain on PCIe bandwidth. Previous-generation GPUs, like the RTX 4090, faced up to a **10% performance reduction** in similar scenarios when limited to PCIe 4.0 x4 or PCIe 3.0 x8, according to evaluations by **Puget Systems**.
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## **Second Benchmark Confirms Outcomes**
The results from TechPowerUp were reinforced by another source: **Hardware Canucks**, a well-known tech YouTuber, carried out similar evaluations on the PCIe scaling of the RTX 5090. Their findings were very much in line with those of TechPowerUp, further substantiating the minimal effect of PCIe downgrades.
### Additional Observations:
– **Rasterization Performance**:
– The performance decline from PCIe 5.0 x16 to PCIe 4.0 x16 was again around **1%**, verifying that rasterization-heavy tasks are largely unaffected by the PCIe interface.
– **Ray Tracing Performance**:
– In ray-tracing scenarios, the performance drop was slightly greater, reaching up to **3%** at 4K resolution. This implies that ray tracing might be a bit more reactive to bandwidth restrictions, yet the impact remains minimal.
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## **Conclusion: PCIe 5.0 Is Beneficial but Not Crucial**
The RTX 5090’s efficiency on older PCIe standards showcases Nvidia’s engineering and optimization prowess.