X-bit labs

NVIDIA GeForce FX 5900XT (SE/LE) Modding Experience (page 2)

Category: Video

by Kirill "ALT-F13" Balalin

[ 06/15/2004 | 03:50 PM ]

Ingredients

This is a full list of all you need to walk in our footsteps:

• One graphics card based around the GeForce FX 5900XT reference design;
• A soldering-iron, wires and other accessories;
• A multimeter;
• Two trimming resistors, 10,000 Ohms each;
• A paper-knife or any other knife with a flat blade;
• Heatsinks for the memory chips of any design;
• Thermal glue, a two-component compound like Arctic Silver Thermal Adhesive or other;
• Something to fasten the heatsinks with;
• A water-cooling system;
• Additional blowers.

Vgpu Modification

My first modification in the “How to make your 5900XT into a racing car” series is a classic Vgpu volt-mod to raise the voltage of the graphics core.

In all 5900XT graphics cards with PCBs of the reference design the Intersil ISL6522CB chip controls this voltage (there are only two above-mentioned exceptions). By the way, the 5900XT differs from the 5900 (without “XT”), which uses a more advanced ISL6569 controller.

Now let me remind you a few basic things concerning volt-modding.

The gist of any volt-modding is modification of the voltage feedback circuit. To do this, a resistor of the necessary resistance is installed between the feedback leg (or some other point of the circuit, if necessary – this usually becomes really necessary when the chip’s legs are not very convenient to solder upon) and the “ground”. Reducing the resistance we increase the voltage of the element.

By the way, and this is very important! If you also use variable resistors, make sure the resistor is set to its maximum, not minimum on the first turning-on! If it is set to its minimum, the GPU will receive the maximum possible voltage and will die immediately in 90% of all cases! So remember this once and for all: reduce the resistance to increase the voltage!

Now, after the preliminaries are over, let’s continue…

Leg 5 of the Intersil ISL6522CB is responsible for feedback. To do the mod, we need to hang a 10,000 Ohms resistor between that leg and the closest ground. There are two more or less good candidates for the role of the ground: the seventh (corner) leg of the same Intersil chip or one of the central pins of the power connector.