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In July 2016, an AnandTech forum teardown found two Sapphire Radeon RX 480 cards sold as 4GB models carrying eight Samsung K4G80325FB-HC25 GDDR5 chips. Those are 8Gb (gigabit) devices, so the boards physically contained 8GB of VRAM. The owner then reported that flashing a compatible RX 480 8GB BIOS with ATI WinFlash made both cards appear as 8GB.
This was a real but limited early-production anomaly—not proof that every Sapphire RX 480 4GB card can be upgraded. The memory markings, PCB, BIOS compatibility and recovery plan all matter.
What the teardown actually found
The original thread documents two Sapphire RX 480 boards with their coolers removed. The inspection reported eight Samsung GDDR5 packages marked K4G80325FB HC25. Eight packages fit the RX 480’s 256-bit memory interface when each device supplies a 32-bit data path.
The thread also identified an IR3567B dual-output 6+2-phase PWM controller, Magnachip MDU1514 high-side and MDU1511 low-side MOSFETs, and a gate-driver part identified as CHiL8510/IR3537. Those observations came from the owner’s photographs and component reading rather than an independent laboratory teardown. The primary record is the original AnandTech discussion.
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- Memory Size: 16 GB
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The important discovery was not the power circuitry. It was that the supposedly 4GB cards had eight high-density memory devices normally associated with an 8GB configuration.
How K4G80325FB proves the physical capacity
Samsung’s marking uses 8Gb to mean eight gigabits per memory chip. That is not the same as 8GB of total graphics memory.
- Each K4G80325FB device provides 8 gigabits.
- Eight devices provide 64 gigabits.
- 64 gigabits divided by eight equals 8 gigabytes.
- Eight 32-bit devices together provide the RX 480’s 256-bit memory bus.
Keep three terms separate: 8Gb per chip is density, 8GB is total VRAM, and 8Gbps is the effective transfer rate. The “HC25” suffix is a Samsung part-number detail; it should not be treated as a complete description of every timing or BIOS requirement.
A later TechPowerUp RX 480 BIOS record associates K4G80325FB memory with an 8192MB configuration: TechPowerUp BIOS record 244185.
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- 2 x HDMI; 1 x DVI-D; 2 x DP
- 256-bit Memory Bus and displays-maximum 5 outputs
- Cooling Technology: Dual Fan
Why a 4GB card could contain 8GB
The available evidence indicates a firmware-imposed capacity limit. The boards had enough physical memory for 8GB, but the shipping 4GB firmware exposed only half of it and reportedly ran memory at approximately 7Gbps rather than the 8Gbps used by the 8GB configuration.
The most plausible explanation discussed at launch was supply and product segmentation. AMD needed a lower-priced 4GB RX 480, while early memory availability may have made higher-density 8Gb parts easier for some board builds than lower-density 4Gb devices. That explanation remains a launch-era hypothesis, not a confirmed AMD manufacturing policy. Contemporary discussion also included reports that AMD rejected the idea that all 4GB cards were physically 8GB.
AMD’s launch material described 4GB and 8GB RX 480 versions based on Polaris 10, with up to 2,304 stream processors and a 256-bit GDDR5 interface. The reference 8GB configuration was associated with 8Gbps memory and 256GB/s bandwidth: AMD’s RX 480 launch announcement.
How the reported 8GB unlock worked
The thread starter said both cards were flashed with a compatible TechPowerUp RX 480 8GB BIOS using ATI WinFlash. Afterward, both were reportedly recognized as 8GB. The continuation of the discussion records the claimed result and the memory-clock differences: AnandTech thread, page 2.
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This is a historical account of a specific pair of cards, not a universal procedure. The thread also notes anomalous GPU-Z information during testing, so a single software screenshot is weak evidence by itself. A stronger verification chain is:
- Read the physical memory markings.
- Confirm that the BIOS identifies the correct memory and 8192MB capacity.
- Check the driver or GPU-Z report.
- Run a workload that actually allocates more than 4GB.
- Test repeatedly for artifacts, crashes and corrupted output.
A BIOS flash does not add memory. It changes how the existing memory is initialized and reported.
Which Sapphire RX 480 cards might be candidates?
Use the following as a screening framework, not a guarantee:
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Plausible candidate
- The board matches the documented early Sapphire/reference-style PCB or is demonstrably compatible with it.
- There are eight physical memory packages.
- The packages carry a compatible Samsung 8Gb marking such as K4G80325FB.
- A matching 8GB BIOS exists for that exact board, memory type, clocks, outputs and power design.
- You have a saved original BIOS and a practical recovery method.
Do not treat it as an unlock candidate
- The card has four memory packages.
- The chips are Samsung K4G41325FE, Elpida EDW4032BABG, Hynix H5GC4H24AJR or another 4Gb/unsupported part.
- The PCB is a different custom design with no verified matching BIOS.
- You cannot recover a failed flash.
- You cannot accept the possibility of losing the card.
Later Sapphire BIOS records demonstrate why the product name alone is insufficient. One genuine 4GB record uses Samsung K4G41325FE and reports 4096MB (TechPowerUp BIOS record 187647); another record shows the same 4Gb Samsung family (record 188577). Other Sapphire 4GB entries list Elpida or Hynix memory (record 268101). Eight chips alone do not prove 8GB: eight 4Gb chips total only 4GB.
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- Memory Interface: 320-bit DDR6
- Form Factor: 3 slot, ATX
- Output: 1 x HDMI, 2 x DisplayPort, 1 x USB-C
- PCI-Express 4.0
BIOS matching and recovery risks
Polaris BIOS files differ in memory vendors, timing tables, clocks, voltage behavior, power limits, display outputs and board layouts. “RX 480 8GB” in a filename is not enough. Match the target image to the exact PCB and memory configuration.
- Bricking: an interrupted or incompatible flash can leave the card unable to boot.
- Instability: incorrect timings may cause artifacts, black screens, driver resets or crashes even when 8GB is reported.
- Recovery difficulty: cards without a dual-BIOS switch may require another GPU, blind flashing or an SPI programmer.
- Warranty: firmware modification can affect warranty coverage.
- False confidence: a successful flash on two cards does not establish a manufacturer-supported upgrade path.
Before any historical experiment, save the original BIOS, record the board and chip markings, verify the recovery image, use a stable power source and avoid interrupting the process. Sapphire’s reference 4GB specification lists one 6-pin PCIe connector, but custom boards can differ: Sapphire reference RX 480 4GB specification.
What 8GB changes—and what it does not
Capacity and bandwidth are separate benefits. More than 4GB can help at higher resolutions, with large texture packs, mods or settings that exceed a 4GB working set. It does not automatically make every game faster.
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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsThe early 4GB configuration was reported at about 7Gbps, while the 8GB configuration used about 8Gbps. At the same 256-bit bus width, 8Gbps corresponds to 256GB/s, whereas 7Gbps is lower. A card that gains capacity but retains a lower memory clock may not behave like a factory 8GB model in every workload.
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The GPU core remains Polaris 10. A firmware change does not add stream processors or transform the card into a faster GPU. Contemporary reports therefore found that 4GB and 8GB models could be close in ordinary gaming, with the advantage depending on resolution, texture settings and application behavior. A contemporary account of the flashable-card story is available at TechSpot.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why this was an early-launch anomaly
The evidence covers two cards inspected in July 2016, not the entire Sapphire RX 480 production run. Later BIOS records show boards built with genuine 4Gb Samsung memory and with Elpida or Hynix devices. Those cards cannot gain physical capacity through software.
The narrow conclusion is the reliable one: some early Sapphire RX 480 4GB boards were apparently fitted with eight Samsung 8Gb chips and could reportedly be reconfigured with an 8GB BIOS. That does not mean all 4GB cards were secretly 8GB, that every 8GB BIOS is interchangeable, or that the modification is safe for an unverified board.
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Does every Sapphire RX 480 4GB have 8GB of hidden memory?
No. Later boards used genuine 4GB Samsung, Elpida or Hynix memory. Physical chip markings and exact board identification are required.
Can a BIOS flash add VRAM to any 4GB RX 480?
No. A flash can expose compatible memory already installed; it cannot turn four 4Gb chips or another 4GB design into 8GB.
Was the reported modification manufacturer-supported?
No. It was a successful owner-reported modification on two cards, with the risks of BIOS incompatibility, instability and failed recovery.
The Bottom Line
The teardown was genuine: two early Sapphire RX 480 cards sold as 4GB carried eight Samsung 8Gb chips, physically providing 8GB. Their owner reportedly unlocked that capacity with an 8GB BIOS, but this remains a rare, hardware-specific launch anomaly—not a dependable upgrade path for Sapphire RX 480 4GB cards generally.
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