This appears to be a Thunder

This appears to be a Thunder IV GX 1152. There were three versions of the Thunder IV GX, the 1600, 1360 and the 1152. The model number designates the first number of the maximum resolution at which the card supports millions of colors. So, e.g., the 1600 supports millions of colors up 1600 X 1200, but the 1152 only up to 1152 X 870. However, the 1152 will display at 1600 X 1200 with reduced color depth.

The Radius Thunder 24/GT (not to be confused with the SuperMac card of similar name) is actually the same as the Thunder IV GX 1152 but the 24/GT lacks the PhotoEngine DSP daughter card.

However, the PhotoEngine DSP daughter card is unusable with PPC processors and IIRC with OS 7.6 and later, so you're really better off removing the DSP daughter card from your T IV GX to reduce heat production and power use.

Testing with MacBench shows that this is the fastest NuBus video card. Yes, it's faster than the MacPicasso 340 which was designed later. However, the MP 340 does beat out the Thunder in a few tests (MacBench has something like 40 video tests), so they're very close. Performance is limited by the NuBus interface in these high end cards.

If you need fast video frames (playing Marathon, e.g.) use built-in video in Quadras and the PDS VRAM card on NuBus PowerMacs. The Thunder will beat them for some business applications, such as scrolling, but for throwing up frames, the PDS VRAM is the fastest way to go.

Even this incredibly engineered NuBus video card, which cost close to $3000 way back when, cannot compete with a moderately performing PCI video card.

It appears that it should be possible to add VRAM chips to convert the 1152 to a 1360 or 1600 but I've never gotten my hands on a 1600 so I could do the necessary comparison.