Rather important question regarding ATI GPU families

[EnigmaTech]

Hey there folks,
I apologise in advance if this question has already been asked/answered I couldn't find it in my travels and google was not my friend today. I've been using the GPU2 and GPU3 clients recently with 2 x Radeon 5770's and had to look into forcing the detection of the GPU via the forcegpu ati flag. However when doing this I ran into a curious issue.. In your instructions on setting up the GPU2/3 client, you say to use the forcegpu ati_r700 for HD 5xxx series cards and forcegpu ati_r800 for the HD 6xxx series cards. However, the HD 5xxx series cards run the r800 or "Evergreen" core, not the r700. The r700 chip was within the HD 4xxx family of cards. The HD 6xxx runs on the "Northern Islands" GPU. So in effect;
f@h GPU Instructions: Actual Chipsets:
Radeon HD 4xxx - auto Radeon HD 4xxx - r700
Radeon HD 5xxx - r700 Radeon HD 5xxx - r800
Radeon HD 6xxx - r800 Radeon HD 6xxx - Northern Islands

Is there a reason for this that will just make me (happily!) look like a silly toad or have the instructions been miswritten?

Thanks for your time!

Marc Hilton
Head of Tech Dept.

[gwildperson]

I suspect that the answer is more closely related to whether you're talking about GPU2 or GPU3 software. The two of them do not recognize the same parameters following the -forcegpu flag. There is no such thing as -forcegpu ati_northern_islands on either one and the option will be ignored. The GPU3 software will recognize ati_r800 but the GPU2 software will not.

I suspect that the drivers and hardware are pretty much backward compatible, so if the FAH software is unable to recognize all of the features of your hardware, it's better to tell it that it's a previous version and use that capability than have it ignore the option entirely and revert to the default feature-support level (HD3000). On the other hand, if you have a hardware feature that can be enabled by a flag that is recognized, it's better to use it than reverting to some kind of driver-level emulation.

[7im]

Hello EnigmaTech, welcome to the forum.

The client and switches are not so much GPU core based in regards as to which -forcegpu flag to use. There are not any 5xxx or 6xxx specialized code yet, so -forcegpu ati_r700 does exactly the same thing as -forcegpu ati_r800.

As noted by Gdub, the v6.23 (gpu 2) client does not recognize the newer -forcegpu ati_r800 switch, while the v6.32+ clients (gpu 3?) recognize all the current switches.

Note: The v6.32+ clients aren't really GPU3 for the ATI cards until we get a GPU3 fahcore to go with it (fahcore_16).

[EnigmaTech]

3. 5xxx series ATI GPUs are supported in the v6.23 or newer FAH client, and requires the 9.10 Catalyst driver or newer. Also use the -forcegpu ati_r700 switch until 5xxx hardware is auto-detected in newer versions of the FAH client. How to add a switch is covered below. Switch requirement fixed in the v6.30 GPU client and above.
4. 6xxx series AMD GPUs are supported, but may require the -forcegpu ati_r800 switch until 6xxx hardware is auto-detected in newer versions of the FAH client.

This is the part I don't quite understand, located at the start of folding.stanford.edu/English/WinGPUGuide. If the 5xxx and 6xxx series are supported as stated in the guide and quoted above but require the switch on some clients to force detection, why does it state to force it to use r700 and r800 respectively when they are both incorrect. I'm not sure about the 6 series, but if the r800 flag exists and the r800 chip is within the 5 series, would it not make more sense to force the particular client to use the correct switch?

3. 5xxx series ATI GPUs are supported in the v6.23 or newer FAH client, and requires the 9.10 Catalyst driver or newer. Also use the -forcegpu ati_r800 switch until 5xxx hardware is auto-detected in newer versions of the FAH client. How to add a switch is covered below. Switch requirement fixed in the v6.30 GPU client and above.
4. 6xxx series AMD GPUs are supported, but may require the -forcegpu ati_rxxx switch until 6xxx hardware is auto-detected in newer versions of the FAH client.

I'm just a bit confused as to why you would force the 5 to use r700 and the 6 to use r800 when 4 uses r700 and 5 uses r800. Then, what confuses the hell out of me.. is halfway down the GPU installation guide, it says this!

* ATI 3xxx series: -forcegpu ati_r600
* ATI 4xxx series: -forcegpu ati_r700
* ATI 5xxx series: -forcegpu ati_r800

I have to say that, if I were in any way less tech savvy I would have been beyond confuses by these instructions.. Perhaps it would be a good idea to correct the initial AMD/ATI section in the GPU guide to avoid this confusion?

[EnigmaTech]

My apologies, posted that before I saw your post 7im. Thanks for your explanation!

[7im]

So the trick here is that when the new series GPU comes out, the existing client doesn't recognize the new hardware, so to get it to fold, you force the client to use the settings of the previous model. (one behind)

However, in a mix mode environment, (mixing 3xxxx and 4xxxx in the same computer) you would set the forcegpu flag of each client to the actual model, not the previous model (this is currently needed in the NV client, but not in the ATI client)

The two different uses of the flag is the confusing part.

[EnigmaTech]

Thanks 7im, you've been a great help!