June 1st 2010 NVIDIA officially announced another Fermi architecture graphic card — GTX 465.
The new card has reduce to 352 number of CUDA cores while having 1024 Mb of memory:
|GTX 465||GTX 470||GTX 480|
|GPU Engine Specs:|
|Raster blocks (ROPs)||32||40||48|
|Graphics Clock (MHz)||607||607||700|
|Processor Clock (MHz)||1215||1215||1400|
|Texture Fill Rate (billion/sec)||26.7||34||42|
|Memory clock (MHz)||1603||1674||1848|
|SDRAM type||1024 MB GDDR5||1280 MB GDDR5||1536 MB GDDR5|
|Memory Interface Width||256-bit||320-bit||384-bit|
|Memory Bandwidth (GB/sec)||102.6||133.9||177.4|
|NVIDIA PureVideo® Technology||yes|
|NVIDIA CUDA™ Technology||yes|
|Bus Support||PCIe 2.0 x16|
|NVIDIA 3D Vision Ready||yes|
|NVIDIA 3D Vision Surround Ready||yes|
|Maximum Digital Resolution||2560×1600|
|Maximum VGA Resolution||2048×1536|
|Standard Display Connectors||2x Dual Link DVI, Mini HDMI|
|Audio Input for HDMI||Internal|
|Standard Graphics Card Dimensions:|
|Height||4.376 inches (111 mm)||4.376 inches (111 mm)|
|Length||9.5 inches (241 mm)||10.5 inches (267 mm)|
|Thermal and Power Specs:|
|Maximum GPU Temperature (in C)||105|
|Maximum Graphics Card Power (W)||200||225||250|
|Minimum Recommended System Power (W)||550 (minimum 38 А on a +12 V rail)||600 (minimum 42 А on +12 V rail)|
|Supplementary Power Connectors||Two 6-pin||6-pin and 8-pin|
A close inspection of both GTX 465 and GTX 470 revealed than GTX 465 differs only by having less memory chips, two, to be exact:
After a short period when the card was announced, Romanian colleagues had found a way to unlock CUDA cores of GTX 465 by flashing GTX 470 bios. After some modifications with GTX 465 bios, all 448 CUDA cores become available, which results in a significant performance growth. Chinese resource chiphell.com continued card modifications by trying to unlock GTX 465 the software way.
Our resource got lucky to obtain the software that unlocks CUDA cores of GTX 465:
We could not test this tool since we had no appropriate graphic card, however, we did found out more about the tool itself.
GTX 465 Upgrade Tool consists of an executable file and NVFLASHWINDOWS 5.95 software. The executable itself has a digital ASUS signature — this means that this tool was created somewhere in headquarters of ASUS laboratories and is not a result of a work of some enthusiast guy. The main idea of the tool is:
- NVFLASH searches for the card with DEVICE ID 0x06C4 ( 465) identification number
- Read its BIOS, NVFLASH uses following key
--filterdevid 0x06C4 -b Log.rom -A -s
- The main software replaces 4 bytes in BIOS. If you can intercept the patched LOG.rom and compare it in Hex-editor with the original BIOS, then you can see what bytes were changed
- Flashes modified BIOS back to the graphic card using this initialization line
NVFLASH --filterdevid 0x06C4 --refreshstraps --overridesub --overrideboard --nopreserve --auto --noconfirm Log.rom -5 -6 -A
In fact, GTX 465 Upgrade Tool flashes GTX 465 with the bios from GTX 470.
Those four bytes that are modified in BIOS stand for the core number configuration of the card.
Therefore, it is not hard to determine BIOS area which is patched by the tool and its changes.
We decide to conduct our own experiment which should reveal the possibility to unlock CUDA cores of GTX 470 to reach the number GTX 480 has. The replacement of target data of GTX 470 BIOS with the configuration of 480 BIOS have not been successful — the number of available cores has not changed. Next we tried something risky — flashed GTX 470 GTX with the 480 BIOS. The card remain to be working, but still no success in core unlocking. From this we can conclude that core configuration of graphic cards based on GPU GF100 is determined not only by BIOS, but also by PCB elements. Most likely shorting some board’s contacts together with BIOS data determines that cherished core configuration.
We, on the other hand, make own conclusions based on the information on Internet about successful results of GTX 465 unlocking to have GTX 470 core configuration — the owners of these cards had all cores originally unlocked, however, the configuration was hidden by the BIOS.
To make final conclusions on possibilities to unlock GTX 465 we need sample of GTX 465 in our lab.
Mo3ulla and Cotulla for analyzing the machine code and help in BIOS modification