4870 Overclocking: Quest to Glory

[Soylent Joe]

Since my 4870 is starting to show its age in many new games, I've decided to try to squeeze out a few more FPS via some mild overclocking. I've never done this before and don't know much about it so I need some help.

Here's my card. It's the IceQ version but I think the cooler is the reference model. It says "4+ Turbo" on the box, referring to the 4GHz memory clock that it's supposed to have but it's only at 1GHz and I don't even think they go that high so I'm not sure what's up with that. Anyways, it runs from 68-75C even under load with the fan on auto. Oh, and I'm using the new 10.3a drivers.

So I opened up ATI Overdrive in CCC, unlocked it, and cranked everything up figuring these weren't drastic increases and that this is a limited tool. I haven't seen any option to go higher than 790/1100 so I guess I'm right. Anyways, I ran the Just Cause 2 benchmark before OC'ing and got 51.01. After OC'ing I got 52.38. It's a very small difference but I was watching my temps and they were exactly the same as stock, so I figured why not leave it overclocked. Next, I played some BC2 and whattayaknow:

Getting artifacts and model glitches up the bum I decided to do some more intensive stress testing. I used the stresser in Overdrive before I did the JC2 benchmark and it passed with no strange temps or errors. Here's the testing:

As you can see in the second one, Furmark was showing some outrageous clocks. It would display the correct 790/1100 then hop to 5177/7208. You can also see GPU-Z displaying those high clocks over in the corner.

Questions

• What's up with the "4+ Turbo"?
• Why were the clocks going from 790/1100 to 5177/7208?
• What do you think caused the BC2 craziness?
• Should I change anything?
• What program would one use to overclock to higher levels than what Overdrive allows?

 

[Soylent Joe]

Bumpity.

 

[EvolvA]

I'm prety sure those artifacts are caused by the frequency of your memory (1100MHz is too much), set the frequency down around 1050MHz and tells us if the artifacts disapeared.

the errors shown in furmark must only be thar, errors...

BTW: it's 1000MHz for memory clock but 4000MHz effective...

 

[heky]

First of all you have to take it step by step. Never just up everything to the max ans go for it. I think you overclocked the memory too much. Lower the clocks of the memory to 1050, and try again. Oh and try using Msi Afterburner for overclocking.

 

[Inioch]

What the other guys said.

When you consider, that the reference memory speed is 900 MHz (3600 QDR), and yours is already factory oc'd to 1000 MHz (4000 QDR), taking it up to 1100 (4400QDR) is probably just too much for it.
If your temps allow it, you can try to up the voltage. I'm not sure if your card supports software voltage tweaking.

Also on these cards, raising the core clock will often result in better increases than the oc'n the memory.

 

[Soylent Joe]

Alright I lowered the memory to 1050 MHz and the core to 785 MHz. I didn't know that it was already overclocked to 1000 MHz from the stock 900. Couldn't the artifacts be caused by my VRAM chips overheating? I'm not sure if there are heatsinks on them or if they're covered by the cooler.

Edit: I looked in and found the memory temp. in GPU-Z while running Furmark again. MEMIO is at about 75C under load. I don't think that's too hot is it? Looking back at the shot where I had the mem at 1100 MHz the memory was at 76C.

Also, the "VDDC Phase #1/#2/#3" are all around 80 degrees. I'm not sure what those are...

 

[EvolvA]

Alright I lowered the memory to 1050 MHz and the core to 785 MHz. I didn't know that it was already overclocked to 1000 MHz from the stock 900. Couldn't the artifacts be caused by my VRAM chips overheating? I'm not sure if there are heatsinks on them or if they're covered by the cooler.

Edit: I looked in and found the memory temp. in GPU-Z while running Furmark again. MEMIO is at about 75C under load. I don't think that's too hot is it? Looking back at the shot where I had the mem at 1100 MHz the memory was at 76C.

Also, the "VDDC Phase #1/#2/#3" are all around 80 degrees. I'm not sure what those are...

75C is normal under load, don't worry

 

[Soylent Joe]

75C is normal under load, don't worry

Alright well these VDDC Phases are hitting like 85C. Do they matter?

 

[Inioch]

Alright well these VDDC Phases are hitting like 85C. Do they matter?

Shouldn't matter. With a stock cooler they hit 100C quite often.

If I remember correclty, MEMIO is located on the core and is not the same as mem chip temp.

So if you don't have any kind of cooling on the memories themselves, except for air under the cooler shroud, they might well be overheating at 1100.

Is 785/1050 stable and doesn't artifact?

Edit: The cooler seems to be pretty much the same as the stock cooler regarding the memory chips. That means nothing special.
I think the only way to increase your overclocks is to change to better cooling. I mean beyond what you get now, 785/1050?

 

[heky]

MEMIO in gpu-z is not memory temperature, its the temperature of the memory controler inside the gpu chip.
Have you had the same artifacts when you lowered the clocks of the memory?

 

[Soylent Joe]

I don't know if it still artifacts with the lower clocks, I'll test it out in a bit. I set the fan on 45% and it cooled everything down quite nicely without a whole lot of noise so I'll keep that setting.