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Uhhhhh...X1600 in iMac horribly underclocked?

A

Alexander

macrumors member
Original poster
Jun 19, 2003
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0
Palo Alto, CA
I just ran ATITool 0.25 Beta 14, and it showed that the X1600 in my low-end iMac was running at 313MHz core, 300MHz memory.

So I overclocked it. It's now stable at (no typo) 440MHz core, 576MHz memory. Yes, that is about 50% faster, and FPS readings back that up.

Keep in mind that the Mobility X1600 is supposed to be clocked around 470MHz core, 470MHz memory. The desktop version of the chip is the same, but is clocked about 100MHz+ faster.

It should be able to be pushed even faster when we actually have the fans running properly.
 
bousozoku

bousozoku

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Jun 25, 2002
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That's a lot but don't you worry about overheating? I think the reason they went with the nVidia chipset originally was because it didn't produce a lot of heat.
 
Josh396

Josh396

macrumors 65816
Oct 16, 2004
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Peoria/Chicago, IL
Wow. I guess the good news about it being underclocked is the performance I'm getting out of it. I've been extremely impressed with the card. However, if I'm able to get better performance out of it I'd love to. How did you go about overclocking it? Also, how big of improvements in FPS did you see and in what game? Thanks a lot.
 
R.Youden

R.Youden

macrumors 68020
Apr 1, 2005
2,093
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I think this may be quite common with Apple hardware, it maybe one of the reasons why the OS is more reliable. It would be interesting to see what happens in the long run. Do any of you board temps increase dramatically with this overclocking?
 
A

Alexander

macrumors member
Original poster
Jun 19, 2003
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Palo Alto, CA
bousozoku said:
That's a lot but don't you worry about overheating?
Click to expand...

No. Overclocking does not increase heat output, unless you start increasing the voltage, which I don't even think you can do without some hardware hacking.

For any given temperature, there is a speed that will be reliable. The reason overclocking exists is that for the max temperature your system is likely to see, that reliable speed is much higher than the speed that the manufacturer decided to run the chip at.

The X1600 in my iMac is clearly FAR underclocked. I was able to push it to 445/585 before it started glitching. Pull it back a few MHz, and voila, stable system.

If, for some reason, my machine ends up running hotter one day (summer?), it may start randomly rebooting, showing graphical artifacts, etc. I will know to decrease the overclocking a little bit at that time.

Alternatively, I could pull the overclocking FAR back from the maximum I observed, to, say, 400/500, and I guarantee you I would never see a problem.
 
Steve1496

Steve1496

macrumors 6502a
Apr 21, 2004
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Yeah, I was just running ATITool too, it can really improve performance. I clocked my core at 440 as well, memmory 540. My iMac was at 380 Core, 320 memmory by default.

In 3D View, it's now showing the 3D effect at 104FPS average!


Steve
 
A

Alexander

macrumors member
Original poster
Jun 19, 2003
96
0
Palo Alto, CA
jamesmcd said:
This doesn't flash the card at all does it?
Click to expand...

No, it's a setting that is automatically reset on reboot. (which is why an OS X overclocker would be useless for XP.) You can set the software to automatically launch and fix the clock speeds on each startup, if you like.
 
Josh396

Josh396

macrumors 65816
Oct 16, 2004
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Alexander said:
Here's the link:

http://www.techpowerup.com/downloads/259

Just download, install, then hit the Find Max Core/Find Max Mem buttons, and give it a while.

Keep in mind that BF2 is a real RAM hog, I wouldn't try playing it with less than 1GB, and 2GB is better.
Click to expand...
I have 2 GB of RAM so I'm okay there. I see the program you linked is a windows program (that or I can't read correctly), have you ran any games on OS X to see if theres improvement there? Or is it just windows specific? Also, (probably a stupid question) could it be possible the drivers made by Apple for Windows affect it somehow? Could they have underclocked it for Windows only? Thanks again.
 
Steve1496

Steve1496

macrumors 6502a
Apr 21, 2004
600
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Just be careful how far you go. I just got this after it froze for about 15 seconds.
 

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A

Alexander

macrumors member
Original poster
Jun 19, 2003
96
0
Palo Alto, CA
Steve1496 said:
Just be careful how far you go. I just got this after it froze for about 15 seconds.
Click to expand...

Yeah, that kind of error is normal after you hit the ceiling. Clearly you'll want to run it a little slower than the speed that caused that. ;)
 
bousozoku

bousozoku

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Jun 25, 2002
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Alexander said:
No. Overclocking does not increase heat output, unless you start increasing the voltage, which I don't even think you can do without some hardware hacking.

For any given temperature, there is a speed that will be reliable. The reason overclocking exists is that for the max temperature your system is likely to see, that reliable speed is much higher than the speed that the manufacturer decided to run the chip at.

The X1600 in my iMac is clearly FAR underclocked. I was able to push it to 445/585 before it started glitching. Pull it back a few MHz, and voila, stable system.

If, for some reason, my machine ends up running hotter one day (summer?), it may start randomly rebooting, showing graphical artifacts, etc. I will know to decrease the overclocking a little bit at that time.

Alternatively, I could pull the overclocking FAR back from the maximum I observed, to, say, 400/500, and I guarantee you I would never see a problem.
Click to expand...

Well, it definitely seems reasonable. I'd like to see it work similarly in the MacBook Pro. Apple generally likes to play it safe. It's good to see that it's possible to go much further.
 
A

Alexander

macrumors member
Original poster
Jun 19, 2003
96
0
Palo Alto, CA
Kingsly said:
What are the clock speeds on the MBP?
What kind of FPS are you getting now that its overclocked? Before you overclocked?
Click to expand...

Test scene in Guild Wars was about 30FPS before, about 47FPS after.

I'd be curious to know about default speed and overclock potential of the MBP as well. You should be able to get into a similar ballpark, since it's the same chip. It's probably cooled differently in the MBP, though.
 
Lord Blackadder

Lord Blackadder

macrumors P6
May 7, 2004
15,669
5,500
Sod off
Alexander said:
No. Overclocking does not increase heat output, unless you start increasing the voltage, which I don't even think you can do without some hardware hacking.
Click to expand...

I disagree - In my experience with a Radeon 7500, 9600 Pro and GeForce 6800GT overclocking can cause temperatures to jump by as much as 20C. For example, when running my GeForce 6800GT at the "stock" speed of 350/1000MHz the card idled around 58-62C, which is warm but not unusual for this card. An overclock to 400/1100MHz produced idle temps of up to 80C, which is a little too hot for daily use without an upgrade to the heatsink-fan setup. Higher average temps = shorter video card lifespan.

Running overclocked day-to-day at hihger temps is less of a concern when you are running a regular desktop video card, but if by some mischance you burn up the GPU in your iMac you're screwed.

I'm not saying don't OC your video cards, just be aware that the risk is substantially higher in Macs with non-upgradable video cards (i.e. all Macs other than the towers). If any of you choose to fiddle with overclocking, make sure to download the Temperature Monitor app from versiontracker and be aware of what your GPU's shutdown temp is - you'll want to stay WELL below that (by perhaps at least 30%) at all times.

IIRC, the X1600 in the iMac is a mobility GPU, so it should be rated for a lower clock than the desktop version. Also, I'm not sure what kind of thermal management the GPU in the iMac gets, so Apple may have cranked the speed down a notch for reliability reasons.

Those claimed FPS improvements are pretty good though - as long as the OC is truly stable it may be something for the gaming enthusiast iMac owner to consider.
 
daveL

daveL

macrumors 68020
Jun 18, 2003
2,425
0
Montana
That's Just Plain Wrong

Alexander said:
No. Overclocking does not increase heat output, unless you start increasing the voltage, which I don't even think you can do without some hardware hacking.
Click to expand...

I'm sorry, but there's no way a chip is going to run at a higher clock frequency and not produce more heat. Think about the physics of it for a moment.
 
D

Demon Hunter

macrumors 68020
Mar 30, 2004
2,284
39
Steve1496 said:
Just be careful how far you go. I just got this after it froze for about 15 seconds.
Click to expand...

Yeah, don't try unless you know what you're doing. Or start saving for a new logic board!
 
Steve1496

Steve1496

macrumors 6502a
Apr 21, 2004
600
0
dferrara said:
Yeah, don't try unless you know what you're doing. Or start saving for a new logic board!
Click to expand...


I would say I know what I'm doing, but I wanted to try things out. Live dangerously:)


Steve
 
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