Introduction to the Xilinx C1100 (Varium C1100)

If you’ve been searching for an affordable entry point into FPGA-based compute acceleration, the Xilinx C1100 deserves serious consideration. Originally marketed as the Varium C1100 and targeted at blockchain applications, this card has found a second life among engineers and researchers looking for HBM-equipped FPGA hardware at reasonable prices.

The Xilinx FPGA C1100 is built on the UltraScale+ architecture, featuring 8GB of High Bandwidth Memory and dual QSFP28 networking ports. What makes it particularly interesting right now is the secondary market—with Ethereum mining no longer viable, these cards are available at significant discounts from their original MSRP.

For those of us who’ve worked with FPGA accelerator cards for years, the C1100 represents an unusual opportunity. You’re getting essentially the same silicon found in the more expensive Alveo U55N, but packaged for a different market segment. The card uses the XCU55N FPGA (same as the U55N), which means you can leverage much of the existing development infrastructure.

Xilinx C1100 Hardware Architecture and Design

FPGA Architecture: UltraScale+ XCU55N

The Xilinx C1100 is built around the XCU55N FPGA, which sits in a package designated FSVH2892. This is a significant device with resources suitable for serious compute workloads. When you’re creating designs in Vivado, you’ll select XCU55N-FSVH2892-2L-E as your target part.

From a PCB layout perspective, the card follows a clean single-slot, full-height, half-length (FHHL) form factor. The passive cooling design means you’ll need adequate server airflow—this isn’t a card you want running in a poorly ventilated desktop chassis. I’ve seen temperatures spike quickly when airflow is insufficient.

Xilinx C1100 Technical Specifications

High Bandwidth Memory (HBM2) Configuration

The 8GB HBM2 on the Xilinx FPGA C1100 provides the memory bandwidth necessary for compute-intensive applications. While it’s half the capacity of the U55C’s 16GB, the bandwidth characteristics remain impressive—up to 460 GB/s theoretical maximum.

For memory-bound algorithms like those used in cryptocurrency mining, scientific computing, and data analytics, this HBM bandwidth is what makes the C1100 competitive. You’re not fighting DDR4 refresh cycles or dealing with rank switching latency—HBM just delivers consistent bandwidth.

200 Gbps Networking with Dual QSFP28 Ports

The dual QSFP28 cages on the Xilinx C1100 support multiple configurations: 8x25GbE, 2x100GbE, or 2x40GbE. Each port comes with its own set of 8 MAC addresses (total of 8 per card), which you can access via the Card Management Solution IP or read from the physical label.

This networking capability transforms the C1100 from a simple compute accelerator into something resembling a very capable SmartNIC. You can process data directly from network interfaces without involving the host CPU—critical for applications requiring line-rate packet processing.

Xilinx C1100 Price: New vs Secondary Market

Understanding the Xilinx C1100 price landscape requires looking at both official channels and the secondary market. The pricing situation has shifted dramatically since Ethereum moved to proof-of-stake, making mining unprofitable and flooding the market with used cards.

Current Xilinx C1100 Pricing Overview

The secondary market, particularly eBay, has become the go-to place for engineers looking to buy Xilinx C1100 cards at reasonable prices. Cards that originally sold for over $3,000 are now available for under $1,200 used. Some listings include custom cooling solutions, which is actually helpful given the card’s passive cooling design.

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Where to Buy Xilinx C1100: Official and Alternative Sources

If you’re ready to buy Xilinx C1100 hardware, you have several options depending on your requirements for warranty coverage, lead time, and budget.

Official Distribution Channels

For new cards with full warranty support, the traditional distribution network remains your best option:

• Mouser Electronics: Part number V-C1100-P00G-PQ-G, though lead times can be extended (300+ days in some cases)
• DigiKey: Stock availability varies; part number 122-V-C1100-P00G-PQ-G-ND
• AMD/Xilinx Direct: Contact sales for volume pricing and availability

Secondary Market Options

The collapse of profitable Ethereum mining has created a buyer’s market for used Xilinx C1100 cards:

• eBay: Most common source for used cards, prices typically $800-$1,200
• Specialty Mining Hardware Retailers: Companies like Jabitaxe offer cards with varying conditions
• University Surplus: Occasionally available from research institutions

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Applications and Use Cases for the Xilinx FPGA C1100

While AMD originally positioned the C1100 for blockchain workloads, the underlying hardware supports a much broader range of applications. The Xilinx FPGA C1100 is essentially general-purpose FPGA compute hardware with HBM and networking.

Blockchain and Cryptocurrency Applications

The card was designed for accelerating Proof of Work (PoW) algorithms and transaction validation in Proof of Stake (PoS) protocols. Xilinx demonstrated impressive results accelerating Hyperledger Fabric transaction validation compared to Intel Xeon Silver 4114 CPUs.

For Ethereum (before the merge), the C1100 achieved approximately 78 MH/s on EtHash at around 104W—competitive efficiency compared to GPUs. Other supported algorithms include CryptoNight variants used by privacy coins.

Research and Academic Applications

The affordable Xilinx C1100 price on the secondary market has made it attractive for university research labs. Use cases include:

• Custom Processor Development: Projects like the EPU (Ethereum Processing Unit) demonstrate building custom 256-bit stack-based processors
• Network Research: The dual 100G ports enable line-rate packet processing experiments
• Algorithm Acceleration: HBM bandwidth enables memory-intensive algorithm research
• ASIC Prototyping: Validate custom silicon designs before tape-out

General Compute Acceleration

Beyond blockchain, the C1100 handles the same workloads as other Alveo-class accelerators:

• Data analytics and database acceleration
• Financial computing and risk analysis
• Signal processing applications
• Machine learning inference
• Network function virtualization

Development Tools: Vivado and Vitis for the C1100

Setting Up the Development Environment

Getting started with the Xilinx C1100 requires installing the Vitis toolchain, which includes Vivado. AMD provides full end-to-end flow support for the Varium C1100 starting with Vitis 2021.2.

Key development resources:

• Vitis Unified Software Platform: High-level C/C++ development without RTL expertise
• Vivado Design Suite: Traditional FPGA development flow for maximum control
• Xilinx Runtime (XRT): Facilitates communication between host and FPGA over PCIe
• XDC Constraints File: Available from the official product page for pin mapping

Programming and Debug Access

The C1100 includes a Micro-USB maintenance port for JTAG programming and UART debug access. This connects to an FT4232H chip providing quad UART/FIFO functionality. You’ll need a Micro-USB cable (not included with the card) to access these features.

A practical tip: when setting up Linux development, check for the FTDI device with ‘lsusb | grep 0403:6011’ to confirm the connection is working.

Xilinx C1100 vs Alveo U55N vs Alveo U50 Comparison

Understanding how the Xilinx C1100 compares to other Alveo cards helps inform purchasing decisions.

The key insight here is that the C1100 and U55N share the same FPGA silicon. The primary differences are packaging, cooling approach, and target market positioning. For engineers comfortable with passive cooling requirements, the C1100 offers excellent value.

Thermal Management and Cooling Requirements

The Xilinx C1100 uses passive cooling, which is both a feature and a challenge. Without adequate airflow, the card will throttle or potentially sustain damage.

Practical thermal management tips:

• Server Environment: The card is designed for high-airflow server chassis, not desktop PCs
• Custom Cooling: Some eBay sellers include aftermarket fans (like San Ace B97) which can help in desktop deployments
• Airflow Direction: Ensure consistent front-to-back airflow across the heatsink
• Power Limiting: For marginal cooling situations, consider limiting power consumption in your designs

Useful Resources and Downloads for Xilinx C1100

Essential documentation and tools for working with the Xilinx FPGA C1100:

1. Official Product Page: AMD Varium C1100
2. Data Sheet (DS1003): Technical Specifications
3. Product Brief: Varium C1100 Overview PDF
4. Blockchain Acceleration GitHub: Xilinx/blockchainacceleration
5. Vitis Software Platform: Development Tools Download
6. DigiKey Listing: V-C1100-P00G-PQ-G
7. Mouser Listing: V-C1100-P00G-PQ-G
8. AMD Support Community: Varium C1100 Forum

Frequently Asked Questions About the Xilinx C1100

1. Is the Xilinx C1100 the same as the Alveo U55N?

The Xilinx C1100 uses the same XCU55N FPGA as the Alveo U55N, making them silicon-equivalent. The differences are in form factor (C1100 is FHHL, U55N is HHHL slim), cooling design, and market positioning. In Vivado, you target the same part: XCU55N-FSVH2892-2L-E. Many U55N development resources work with the C1100.

2. What is the current Xilinx C1100 price on the secondary market?

The Xilinx C1100 price on the secondary market (primarily eBay) ranges from $800 to $1,200 for used cards as of late 2024. This is significantly lower than the original MSRP of $2,500+ due to the end of profitable Ethereum mining. New cards from official distributors remain in the $2,500-$3,500 range with extended lead times.

3. Can I use the Xilinx C1100 in a standard desktop PC?

Technically yes, but with important caveats. The card is passively cooled and designed for high-airflow server environments. In a desktop, you’ll need to add active cooling (aftermarket fan solutions are available) and ensure adequate airflow. Many users on the secondary market sell cards with custom cooling already installed.

4. What development tools do I need for the Xilinx FPGA C1100?

You’ll need the Vitis Unified Software Platform (which includes Vivado) version 2021.2 or later for full C1100 support. Additionally, install the Xilinx Runtime (XRT) for host-FPGA communication. The XDC constraints file for pin mapping is available from the official product page. A Micro-USB cable is required for JTAG/UART access.

5. Where can I buy Xilinx C1100 cards with confidence?

For new cards with warranty, buy Xilinx C1100 from authorized distributors: DigiKey, Mouser, or AMD directly. For used cards at lower prices, eBay is the primary source—look for sellers with good ratings and clear return policies. Specialty retailers like Jabitaxe also carry these cards. Always verify the part number V-C1100-P00G-PQ-G matches your order.

Conclusion: Is the Xilinx C1100 Right for Your Project?

The Xilinx C1100 occupies an interesting position in the FPGA accelerator market. Originally designed for blockchain, it now offers excellent value for engineers seeking HBM-equipped FPGA compute at accessible prices.

If you’re looking to buy Xilinx C1100 hardware, the secondary market presents a compelling opportunity. Cards that cost $3,000+ new are available for under $1,200 used. For research, prototyping, or learning FPGA development with real HBM hardware, this price point removes significant barriers to entry.

The practical considerations—passive cooling requirements, the need for proper development tools, and understanding the silicon is shared with the U55N—are manageable for most engineers. The Xilinx FPGA C1100 delivers genuine data center-class acceleration capability at a fraction of typical costs.

For production deployments requiring warranty support and guaranteed availability, the official distribution channels remain the safer choice despite higher costs and lead times. But for development, evaluation, and research applications, the current market conditions make the C1100 one of the most accessible paths to HBM-equipped FPGA acceleration available today.