Odd advice from tech support

[Angilion]

Tech support for a company I won't name has been getting a fair few calls about their 7800GT cards. There is an unusual amount of instability issues and the 100% fan speed issue seems universal on some revisions of their cards. I've found one claim of working fan control on these revisions.

Anyway, here's some great advice from that company's tech support about the stability issue:

i) You must have a PSU that supplies at least 25A on a single 12V rail. PSUs with dual 12V lines probably won't work properly with these cards.

ii) DX9-based games will run fine with the card at stock speeds, but you will have to underclock it to run OpenGL-based games stably.

Gotta laugh, I suppose.

 

[Angilion]

Good point, nikebee. It's XFX. Personally, I think that their tech support is flakey. I see no reason why a PSU with 2 12V rails can't work properly with a 7800GT. I also think their products are flakey - the use of a molex connector on a PCI-E card is odd and the UDE* revision cards seem to be throwing up more problems than is normal, especially the lack of fan speed control. I have not seen a single claim of the UDER revision having working fan speed control at all - does anyone here have such a thing?

It is even being considered (on XFX's forums, at least until they delete the thread) that the versions of the cards with lots of LEDs don't have fan control at all. The LEDs are powered from the same wires as the fan (a simple split after the power header) and the LEDs require 12V. Metering shows 12V being supplied to the fan at all times.

Daz...my PSU is spec'd for 26A on a single 12V line, so it is possible. It won't all be going over the same wire, so the guage is heavy enough. The recommended limit in the ATX spec is 18A per 12V rail, though.

 

[Angilion]

Raikiri...do you have working fan speed control on a UDE3, UDE7 or UDER revision card? I'm trying to find out if it's possible.

 

[Angilion]

I have just bought a XFX 7800GT and have a Enermax PSU with two 12V rails

I have changed the retail fan for a Zalman VF700-Cu and that runs of the PSU so I think I will be fine or is there another problem

I can't use my machine as my memory is RMA'd and I have no CPU yet.

Power-wise, I think the only thing you'll have to watch out for is how you connect components that use a molex connector, if you have the XFX 7800GT revision that uses a molex connector rather than the standard PCI-E power connector. If you have a version with the standard PCI-E power connector, I doubt if that would be a problem as long as your PSU has enough power output for the two 12V rails combined.

If you have the molex version, it would be a good idea to not have anything else on a molex connector on the same cable as the one you put in the card. 18AWG cable (which is probably what you have for your Molex connectors from your PSU) plus PCI-E slot can supply enough power for an o/c 7800GT card with some LEDs on it, but there isn't much left over. Having anything else powered from the same cable, unless it uses very little power, might cause stability issues.

 

[Angilion]

You might like to look over on XFX's forums. The main thread about the most common problem (no fan speed control) was deleted by XFX, but there are many others.
Most people seem to be circumventing the 100% fan speed on the XFX 7800GT Extreme Noise Edition in the way you did - fitting another cooler.

This should cheer you up a bit, Dutch Guy - there are very few stability/artefacting/etc issues being reported with the UDER revision. Almost all the people reporting them have the UDE7 revision.

 

[Angilion]

Yes, there are very few complaints about that version, just the odd few you'd expect from anything. It's the UDE models that have an unusual number of problems. What is odd is that UDE7 and UDER models are newer than the UDF7 model, so XFX have introduced problems rather than fixing problems.