Tantalum caps from a good quality late 90's device are not going to spontaneously combust any time soon - I'm not sure why you are so anxious; caps like these are in many vintage devices you probably own and not needing replacement. In the rare event they do blow, the damage is often just around the tantalum cap footprint itself and easily replaced.

Is this really 8Mb ? looks like 4Mb
isnt 8Mb ZX SDRAM only ?

No, the ZX exists in SGRAM form as well and it's the one to look for as the SDRAM version is only 64bit and thus very slow.

Yea, says 8MB in the bios message at post as well as DirectX config in Windows 95. Datasheet for the memory chips show they are 2MB SGRAM.

https://pdf1.alldatasheet.com/datasheet-pdf/v … 636327Q-10.html

I went ahead and ordered the aluminum poly caps, as well as a new e-cap to replace that tiny 4mm SMD one which is likely dried out. I know I am being paranoid, but these things are 22 years old at this point and I don't want to risk the destruction if one of the tants shorts out. I'll post an update once they are replaced.

Riva 128ZX came in 3 flavors:
4 Mb SGRAM 64-bit bus (only 2 chips on board)
8 Mb SDRAM 64-bit bus
8 Mb SGRAM 128-bit bus

Replaced the caps, perfect fit-wise. And even though the polymer are much lower ESR, it didn't seem to effect anything. Output is still great.

I've been looking to put tantalums into any retro video card I can, and have so far seen only the Viper 330 come with what look like derated tantalums. The 10 uF 25 V caps would be 16 V in Rivas that use wet alus, and other tantalum-using variants I've seen have 16 V as well. I assume these parts see about 12 volts in use, so 25 V agrees with the modern paranoid recommendation of 50% derating, not likely to fail in a lifetime. The other tantalums might expect to see some 5 volts I'm guessing, so their 16 V is plenty headroom as well.

Are there other retro graphics cards besides the Viper 33o where the tantalums were derated by more than the alternative wet alus?

vvbee wrote on 2025-03-24, 10:24:

I assume these parts see about 12 volts in use, so 25 V agrees with the modern paranoid recommendation of 50% derating, not likely to fail in a lifetime.

No, the 12 Volt fingers on the PCI connector are not populated. The highest voltage the caps on this card will see is 5 Volt.

True, with a multimeter my Viper 330 PCI measures 5 volts across the 47 uF next to the VGA connector and 3 volts on the smaller ones, on the DOS bootup screen anyway. C52 I didn't measure because of a larger heatsink in the way. This card is a later revision than the OP's and the 10 uF tantalums are rated for 35 V, not sure why Diamond chose to seemingly over-derate the 10 uF like this. Could just be availability but I'd imagine 35 V tantalums were much more expensive than the 16 V others seem to have used. Also raises the question why even 16 V if the baseline expectation in use is 3 volts.

The Serpent Rider wrote on 2020-08-07, 15:09:

Riva 128ZX came in 3 flavors: 4 Mb SGRAM 64-bit bus (only 2 chips on board) 8 Mb SDRAM 64-bit bus 8 Mb SGRAM 128-bit bus […]
Show full quote

Riva 128ZX came in 3 flavors:
4 Mb SGRAM 64-bit bus (only 2 chips on board)
8 Mb SDRAM 64-bit bus
8 Mb SGRAM 128-bit bus

I’m guessing this is a Riva 128ZX with slow SDRAM 🙁 ?

No, that is quite clearly SGRAM.

Garrett W wrote on 2025-03-25, 10:43:

No, that is quite clearly SGRAM.

Wow I’m shocked. I got the card for a good price and it’s not a fancy Diamond one. I was convinced it had the slow memory. I’m a memory noob. How do you tell if it’s SGRAM or SDRAM?

Usually by memory package. This is clearly SGRAM package. SDRAMs are normal rectangular chips, same as motherboard RAM.

Wow I’m shocked. I got the card for a good price and it’s not a fancy Diamond one.

Riva 128ZX was never a premium card to begin with. It was a budget rehash.

The Serpent Rider wrote on 2025-03-25, 11:51:

Usually by memory package. This is clearly SGRAM package. SDRAMs are normal rectangular chips you can see on motherboard RAM sticks.

Ok I’m confused, the chips on this card are rectangular so that means it’s SDRAM?

zuldan wrote on 2025-03-25, 11:55:

The Serpent Rider wrote on 2025-03-25, 11:51:

Usually by memory package. This is clearly SGRAM package. SDRAMs are normal rectangular chips you can see on motherboard RAM sticks.

Ok I’m confused, the chips on this card are rectangular so that means it’s SDRAM?

I think he was referring to the package type. SDRAM of this vintage is SOP/TSOP package (pins on two opposing edges of the package). SGRAM is QFP typically (pins on all 4 edges).

The Serpent Rider wrote on 2025-03-25, 11:51:

Riva 128ZX was never a premium card to begin with. It was a budget rehash.

Anything with tantalums instead of cheaper options is premium by definition.

*laughs in old motherboards going in flames with tantalum caps*

The Serpent Rider wrote on 2025-03-25, 20:19:

*laughs in old motherboards going in flames with tantalum caps*

Far more likely to see degraded alus corroding the board and repeated cycles of thermal stress to keep replacing them.

Tantalums really just hate being left idle for a long time. If they get routine use then they'll probably last forever. But now that these devices have graduated to a sleepy lifestyle, we do see how angry they can be about waking up again.

vvbee wrote on 2025-03-24, 19:47:

True, with a multimeter my Viper 330 PCI measures 5 volts across the 47 uF next to the VGA connector and 3 volts on the smaller ones, on the DOS bootup screen anyway. C52 I didn't measure because of a larger heatsink in the way. This card is a later revision than the OP's and the 10 uF tantalums are rated for 35 V, not sure why Diamond chose to seemingly over-derate the 10 uF like this. Could just be availability but I'd imagine 35 V tantalums were much more expensive than the 16 V others seem to have used. Also raises the question why even 16 V if the baseline expectation in use is 3 volts.

The parts were ordered in bulk for any card Diamond might make, so they probably wanted a cap they could use safely on 12V if some card needed that. It would make sense for them to order a bulk supply of 10uF 25V, not sure why they went up to 35V though - maybe just the way pricing and availability was at that moment.
If 10V or 16V was appreciably cheaper then they could have stocked multiple voltages of course. But there's also an advantage to reducing the number of different parts that the machines have to handle separately.

I don't know if Diamond did their own manufacturing or just contracted it out. If it was outsourced then who knows what else that manufacturer was building, so maybe for them 35V was handy and Diamond would have listed them as acceptable.