6.5 inches for this model # 512-P3-N956-TR. Here's how I found out in case that's not the right model:
1. Go to www.evga.com (click continue... hehe)
2. Click products
3. Select GeForce 9 Series
4. On the list to the right, find the exact model number of the card you're interested in buying (they list 3 cards based on the 9500 GPU currently in production)
5. Click "More Product Information"
6. Click "Dowload PDF Spec Sheet" (Adobe Reader required) and read the Dimensions portion.
As an aside, for the price difference vs performance, you may want to look into the 9600GT. Typically they're only 10-20 dollars more while offering significant performance gains.