Radeon HD 5770 vs GeForce GT 640

Speed and memory

In our performance index the Radeon HD 5770 scores 1.4 and the GeForce GT 640 scores 1.2, which makes the Radeon HD 5770 about 17% faster. That is a visible but modest gap, usually 5 to 10 fps in a game that runs at 60.

The Radeon HD 5770 has 1 GB of video memory and the GeForce GT 640 has 2 GB. That difference matters at 1440p and in new games at High textures, and it can outweigh a small speed advantage as the card ages.

In our estimates for popular games at 1080p on High, the biggest gap is in Cyberpunk 2077 (3 against 2 fps), and the smallest is in Fortnite (19 against 17 fps). Games that are light enough to run above 200 fps on both cards show little difference at all.

Power and value

The Radeon HD 5770 is rated at 108 W and the GeForce GT 640 at 65 W. With a mid-range processor that means a power supply of about 450 W for the first and 450 W for the second. The power draw is close enough that cooling and noise will be similar.

At launch the Radeon HD 5770 cost $159 and the GeForce GT 640 $99. Per dollar, the GeForce GT 640 gave more performance (1.2 points per $100 against 0.9). Current prices differ, so run the same sum on what you can actually buy today.

Which one to buy

Choose the Radeon HD 5770 if you want the faster card, and you can accept 1 GB of memory. It makes the most sense at 1440p and above, or on a monitor with a high refresh rate.

Choose the GeForce GT 640 if the price gap matters more than the 17% speed difference, and you value the extra video memory. Whichever you pick, check reviews for the games you play, because two cards with similar scores can differ in individual titles.