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BFG GeForce 7800GS OC 256Mb AGP:
Review and Testing

Paul V. Bolotoff
Release date: 1st of December 2006
Last modify date: 23rd of May 2007


Setting Up and Overclocking

The testing job has been performed on the following hardware:
  • processor: AMD Athlon 64 FX-51 (Sledgehammer, rev. C0, 130nm SOI) 2.44GHz (11x222MHz)
  • mainboard: ASUS SK8V (VIA K8T800, Socket 940, BIOS rev. 1002)
  • memory: Mushkin High Performance 2x512Mb PC3200 DDR SDRAM ECC registered 222MHz
    (tCAS=2, tRCD=3, tRP=2, tRAS=6, tRC=8, tRFC=14, tWR=2, tR2W=1)
  • HDD: Western Digital 800JB (IDE, 80GB, 8Mb of cache memory)
  • DVD-RW drive: TEAC (actually, Lite-On) DV-W516G (IDE, 2Mb of cache memory)
  • sound card: Turtle Beach Montego II PCI (Aureal Vortex 2)
  • PSU: InWin 430W (IW-P430A2-0 — 32A at +3.3V, 35A at +5V, 18A at +12V)

Nothing outstanding these days, but about 3 years ago this configuration has been on the top of gaming performance. However, most of AGP-based systems aren't any better, so why not? Let's see how fast it handles modern tasks.
As you may have guessed already, this hardware has been overclocked. Standard settings of the processor are 2.20GHz (11x200MHz) and 1.50V core voltage. This is the fastest processor of the K8 core rev. C0, so it hasn't been an easy task to make it running significantly faster with neither water nor phase-change cooling. Firstly, all major capacitors related to the processor stabiliser have been replaced: 3 Nippon Chemi-Con KZE 1200µF/16V liquid electrolytes for 3 Sanyo WG 1800µF/16V liquid electrolytes with 1 Fujitsu RE-SU 330µF/16V solid electrolyte installed additionally; 6 OST RLX 1500µF/6.3V liquid electrolytes for 6 Rubycon MBZ 2200µF/6.3V liquid electrolytes with 3 Sanyo SP 560µF/4V solid electrolytes and 3 EPCOS 220µF/10V tantalum ones installed additionally. However, it has been a question of about 50 MLCCs (10µF ones mostly) installed wherever possible to make the processor really happy with 1.70V core voltage. Although there were several thick copper wires placed on the mainboard's back side to decrease voltage losses even further. The mainboard's BIOS doesn't allow to go over 1.70V, and the author hasn't got neither time nor intention to play with earth levels of the processor's PWM controller to work around this obstacle. By the way, many of the other electrolytic capacitors on the mainboard have been also replaced with better ones. Secondly, Thermaltake Big Typhoon air cooling system (copper base with 6 heat pipes coming to 140 aluminium ribs and a 120mm dual ball bearing fan at 1300rpm) chosen for this processor has undergone an upgrade with a Titan TFD-12025H12B 120mm dual ball bearing fan at 2200rpm, and the resulting 2-fan monster has been taken together with 70mm screws and 5mm fluorine-plastical pads. Still quiet, but much more effective now. Thirdly, the processor's heat spreader has been removed, and the cooling system's bottom surface has been polished thoroughly in order to achieve a proper contact. As a result, a significant decrease in the maximal core temperature (from 58 °C initially to 52 °C with two fans and to 42 °C with the bottom polished and no heat spreader; that's in winter, add up to +15 °C for summer). In fact, there is no sense in removing a heat spreader and attaching a rough radiator's surface afterwards. Fourthly, some memory timings have been reduced from those set by default, even the overclocking hasn't been an problem — those W942508CH 5ns memory chips by Winbond are good ones, it hasn't been necessary even to increase their voltage from default 2.6V. Despite all efforts, the HyperTransport bus speed has got to be reduced in the BIOS from 800MHz to 600MHz (666MHz with the overclocking), otherwise the whole system would hang up deadly from time to time even under low software activity. Both ECC mode of the system memory and Cool'n'Quiet mode of the processor have been disabled to maximise performance. VIA KT8T800 system logic doesn't support AGP/PCI lock feature, unlike K8T800 Pro (in theory at least), thus speeds of the AGP and PCI buses have risen from 66MHz and 33MHz to 74MHz and 37MHz respectively, though it hasn't caused any trouble.
AMD Athlon 64 FX-51 on ASUS SK8V Back side of this ASUS SK8V
(the testing system) (the mainboard's back)

A non-localised 32-bit Windows XP Professional SP1 with DirectX 9.0c (4.09.0000.0904) has been installed, also NVIDIA ForceWare 91.31 and ATI Catalyst 6.9 drivers with their settings as the following:
NVIDIA ForceWare 91.31
Anisotropic filteringApplication-controlled
Anisotropic optimisation  Off 1
Anisotropic sample optimisation  Off 1
Antialiasing settingsApplication-controlled
Conformant texture clampOn
Extension limitOff
Gamma corect antialiasingOff
Hardware accelerationSingle display performance mode
Image settingsBest quality
Negative LOD biasOff
Transparency antialiasingOff
Trilinear optimisation  Off 1
Triple bufferingOff
Vertical syncForce off
 1  After switching Image settings to Best quality these optimisations get disabled, and even if enabled manually they're of no effect.

ATI Catalyst 6.9
Anisotropic filteringApplication managed
High quality anisotropic filteringDisabled
Anti-aliasingApplication managed
Adaptive anti-aliasingDisabled
Mipmap detail levelHigh quality
Catalyst A. I.  Disabled 2
Wait for vertical refreshAlways off
 2  This setting disables internal filtering optimisations.

Only control panel options of both drivers have been tuned. No manual system registry tweaks or any third-party software have been involved in order to change any hidden options. Therefore, all video cards by NVIDIA and ATI about to be tested have been set up to compete fairly.
BFG GeForce 7800GS OC 256Mb AGP has shown good overclocking results. It has been stable completely at 480.9MHz of the graphprocessor and 355.7MHz (1422.9MHz effective) of the video memory, i. e. +20.7% and +13.3% respectively — endless hours spent on various hard-boiled games have proved this statement. As you can see, the video memory has been able to unleash its 1.4ns potential. One must say that it has been a simple overclocking which doesn't involve any changes in a video card's BIOS including voltage levels, memory timings or geometrical delta (by the way, it is set to zero). Of course, it doesn't come even remotely close to hardware voltage modifications also known as voltmodding. Only fan speed has been adjusted in High Power 3D mode from 80% to 100% after the overclocking. The cooling system supplied has proved its efficiency: the maximal temperature of the graphprocessor has been able to reach 58 °C before the overclocking and 60 °C after (10-loop Nature test of the 3DMark2001SE suite has been used for the purpose of heat-up). Now about other cards which are about to enter our testing.
ASUS GeForce 6600GT Top 128Mb AGP has been chosen because GeForce 6600 series cards are the most widespread ones since GeForce 2MX series. This video card is based on a NVIDIA NV43 graphprocessor clocked at 550.8MHz with 128Mb of GDDR3 SDRAM clocked at 274.2MHz (1096.9MHz effective) and a PCIe to AGP bridge (HSI). It must be the fastest GeForce 6600GT out there, though the official web-site states that these video cards come with graphprocessors clocked at 520MHz, so this sample is a little faster. Whatever the reason is, it has been decided to leave the graphprocessor clocked at 550MHz. In general, NV43 features 8 pixel/texture pipelines, 3 vertex pipelines and 4 raster operators. It consists of 146 mln. transistors and is manufactured using a 110nm technological process.
Sapphire Radeon X1600 Pro 256Mb AGP has been chosen simply because at the time of testing (October-November of 2006) there has been no other AGP based video card by ATI to support SM 3.0. It comes with an ATI RV530 graphprocessor clocked at 499.5MHz, 256Mb of DDR2 SDRAM clocked at 202.5MHz (810.0MHz effective) and a PCIe to AGP bridge (RIALTO). In general, RV530 features 3 sets of 4 pixel pipelines each, 5 vertex pipelines and 4 texture pipelines with a raster operator each. It consists of 157 mln. transistors and is manufactured using a 90nm technological process with low-capacitance (low-k) dielectrics.
Note that both ASUS GeForce 6600GT Top and Sapphire Radeon X1600 Pro haven't been overclocked. It's worth to mention that these video cards accommodate 128-bit data buses of video memory while BFG GeForce 7800GS OC runs a 256-bit implementation.
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Copyright (c) Paul V. Bolotoff, 2006-07. All rights reserved.
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