X-bit labs

Sparkle SF-PX88GT256D3-HP Graphics Card: Is 256MB Enough? (page 3)

Category: Video

by Alexey Stepin , Yaroslav Lyssenko

[ 02/28/2008 | 04:25 PM ]

PCB Design and Specifications

The Sparkle GeForce 8800 GT 256MB resembles the GeForce 8800 GT 512MB and uses the reference PCB design. The card is blue rather than green as most cards manufactured for Nvidia are.

We could find no differences in the PCB wiring. A four-phase Primarion PX3544 controller is responsible for the power supply of the GPU and one of its phases is not installed just like on the Nvidia GeForce 8800 GT 512MB. An Intersil ISL6549CBZ chip is responsible for the memory chips. Like the reference GeForce 8800 GT 512MB, this card is equipped with one 6-pin PCI Express 1.0 power connector.

The Sparkle card is equipped with GDDR3 memory manufactured by Quimonda. The HYB18H256321BF-14 chips have a capacity of 256Mb (8Mb x 32) and a voltage of 1.8V. Eight such chips make up a 256MB memory bank accessed across a 256-bit bus. For an access time of 1.4 nanoseconds the rated frequency is 700 (1400) MHz, and this is the frequency the memory is actually clocked at (it is also the same as the memory frequency of the reference GeForce 8800 GT 256MB). So the memory bandwidth of the junior GeForce 8800 GT is considerably lower at 44.8GB/s as opposed to 57.6GB/s of the senior model. This may have a negative effect on the card’s performance at high resolutions and with enabled FSAA. Already clocked at their rated frequency, the memory chips seem to lack any overclocking potential, but we had a nice surprise with them as you’ll learn shortly. Some makers may install faster memory on their versions of GeForce 8800 GT 256MB because the GPU developer doesn’t impose strict limitations in this respect.

The GPU is revision A2 like the GPUs of all the versions of GeForce 8800 GT 512MB we have tested before. This sample is dated the 41st week of the last year (October 7 to 13). The GPU configuration is the same as on the GeForce 8800 GT 512MB: 7 active computing blocks with a total of 112 unified shader processors, 28 TMUs and 16 ROPs. To remind you, each of the G92’s TMUs has two address and two texture filter units, which theoretically means a total of 56 TMUs. However, real applications imply the use of tri-linear and anisotropic filtering, and these 28 TMUs may prove to be even less efficient than the 32 TMUs of the G80 chip in which there are two filter units per each texture address unit. The main domain frequency is 600MHz, the shader domain frequency is 1500MHz. The Sparkle GeForce 8800 GT 256MB doesn’t differ in anything from the reference GeForce 8800 GT 512MB in this respect.

The seat for a DisplayPort chip is left empty as the card is equipped with two standard DVI-I connectors supporting dual-link mode. The Sparkle supports the audio-over-HDMI feature by means of the 2-pin white plug, located near the MIO connector. It can be connected to the SPDIF connector of your sound card. An external adapter can probably be used as well, like with the Gainward Bliss 8800 GT 512MB GS GLH, but neither this adapter nor a DVI-I → HDMI adapter is included into the box. The 7-pin mini-DIN port outputs analog video in S-Video, Composite and YPbPr formats. The latter format is the analog version of HDTV which has lost popularity due to the arrival of HDMI.