What do you think I should OC my DDR2 VRAM?

For overclocking my ATi HD 2600, I've settled at 600mhz for the core as I can judge that from the temperature. I've been overclocking it since November (when I got Crysis ), and for the first 5 months I always overclocked the memory to 500mhz with no problems. Then I undervolted and overclocked the CPU, which actually increased my GPU's temperature by about 1 degree because the fan was less active (less CPU heat), so I decided to go back to 450mhz for the memory (just to be safe). But I was testing Bioshock today at 1280x800 and it does run better at 500mhz (though can't measure framerate). Crysis benefits only by 1/2fps going from 450 to 500 though so I'm not sure it's worth it.

The desktop HD 2600 Pro DDR2 has no cooling on the VRAM, but runs at 500mhz. Pictures of the HD 2600 in the HP 8510p show it has some cooling covering the VRAM and I have a notebook cooler, so should I stop worrying and go back to 500mhz? Or even go past that until I get artifacts so I know where the limit is?

Thanks.

 

Take the vRAM as high as you can get it without artifacts. When it first artifacts, you've not done any damage, but you know its too hot. Running that high too long will hurt the GPU.

Use AtiTool to check for artifacts. It is the best memory testing application for GPUs on the market. Just take up the memory clocks until you get artifacts! Happy Overclocking! (Make sure your fans are on max )

 

I've got ATi Tool 0.27 Beta 3, but never installed it as I don't like installing extra programs. I've just been using AMD GPU Clock Tool v0.7 and now v0.9.8 (new version works very well, v0.7 sometimes caused the display driver to briefly stop responding). I heard Crysis is very good at stressing the GPU; it's the only game that caused my OC to reset after 2 hours of playing (only happened once), could I just use that instead?

 

You could use it, but many times you don't see artifacts. ATI Tool uses an artifact detecting api that shows artifacting and lets you know any time there is any at all. If you want your card to last a while and get top performance out of the card, install ATI Tool. It won't hurt anything.

 

I agree, you might not notice small artifacts in Crysis and it's a hassle to run every time you change your clocks. Besides, you can always uninstall ATI Tool after you reach clocks that you're satisfied with.

 

Ok, thanks. I'll give it a go and let you know how I get on.

 

ATI Tool is a great utility, it's worth installing for the artifact finder alone.

A word about overclocking GPUs - most of the heat increase is going to come from overclocking the core.

Have you tried overclocking the shader clock?

One thing to note is that different games are going to respond differently to overclocking. Some games might benefit more from a fast core, and some from memory as you already found. You can make various overclocking profiles for your games.

Here is how I would proceed to get the best gameplay experience. Make sure you watch your temperatures and check for artifacts using ATI Tool every step of the way. I'd go in 5 - 10MHz increments, then run ATI Tool for a few minutes to verify temps + stability (no artifacts). As you get higher, run the artifact tester for longer periods.

Now, about those profiles. My suggestions:

1. Set the clocks to default and start overclocking the core; go as far as you can, following the instructions above. When you can't go any higher, run 3DMark06, and each of the games you frequently play. Use FRAPS ( www.fraps.com) to record framerates in your games (F11 starts a benchmark; set FRAPS so it only benchmarks for 60 seconds and records min/max/avg), then access the text logfile it creates in its default directory to get the results.
2. Do the same as #1, but for memory.

I'd save shader overclocking for last.

3. Now try a few combinations of core + memory overclocks. Record the performance changes.

Then you have to analyze the performance changes from overclocking. This is the tougher part. Your analysis might be along the lines of "A 15% increase in the core clock in Crysis yielded a 10% performance improvement, where a 15% increase in memory clocks only yielded a 5%. Various combinations of memory+core overclocks yielded 3 to 6% performance increases. For this game, the best setting is the core overclock only."

And you'd do that for each game.

Hope that helps. Again, watch those temps.

 

Thanks for the detailed reply Chaz. I've been running ATi Tool and tried scanning for artifacts at 600/450 for 5 minutes and 600/500 for another 4/5 minutes and it was fine, so I tried the find max memory clock (core still at 600) and as soon as it went to 549mhz, I started getting artifacts all over the screen so quickly aborted and reset default clocks again. I was overclocking and stressed my CPU with wPrime at the same time to generate as much heat as possible. Temps for the CPU were around 58 most of the time (60 max) and generally 46/47 for the GPU. The max temp for the GPU was 52 degrees, but that wasn't while I wasn't doing anything (the fan was off). So from this result, 500mhz memory should be ok?

P.S Going to watch MotoGP now, or I'll miss it .

 

Those temperatures are great. As long as your GPU temps are under 80*C and your CPU under the max (should be listed in CoreTemp as the Tj. Max value), you're fine. That notebook has a great cooling system.

Once you achieve your maximum overclock, I'd back off 10MHz or so and use that as your overclock profile. The reason is, if you stick with the absolute max clock, one game could push it to artifact whereas with a 10MHz less clock, you have a buffer against that.

You may be interested in this tool: HWMonitor:
http://www.cpuid.com/hwmonitor.php
It's a standalone temperature monitor for various devices. Works great on all my systems, and it keeps track of the max for you.

I would leave the CPU at stock for your GPU testing; don't introduce more variables than necessary. Once you get your GPU settings finalized, then bring back the CPU OC. I am curious, does your memory auto-overclock with the CPU? I have not overclocked AMD before.

 

I've always used HWMonitor, it is indeed a great program. I sometimes leave it running whilst gaming to get my max temps, but doing this testing enabled me to watch the temps whilst stress testing, so I get a better idea of the temps its running at which is good to know.

The RAM speed does increase when overclocking the CPU by the FSB, but the Turion TL-56 runs DDR2 667 (effective) at 300mhz (real) on its max multiplier (x9). Overclocking the CPU to 2ghz puts the ram back to 333mhz, so I'm not actually overclocking the RAM.

Edit: I just tried finding the max overclock for the core and it got upto 796mhz!! I had it set so ATi Tool won't go over 800mhz. It stayed there for a few minutes (with memory at 500mhz & CPU overclocked and stressed with wPrime) before I got a few flashes of yellow in the test window, but with no errors detected, so I reset the core speed back down to 500mhz. Max temperature was 51 degrees! But after this I though I'd like to get a screenshot in case anyone didn't believe me, so I tried again straight away, but the core only got back upto 749mhz before the laptop froze & I had to force it to switch off. The HD 2600 is amazing at overclocking! Maybe I should run the core at 650mhz - it's still 100mhz under the limit!