24" 7600GT Overclockability...

MacProGuy

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Aug 16, 2006
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Ok... just thought I'd share...

The stock Apple supplied nVidia 7600GT on the 24" iMac clocks in at 500Mhz Core speed and 575Mhz Memory speed...

Using the "Coolbits" registry edit, I have enabled the built-in nVidia over clocking utility.

There is a *detect optimal frequencies* button, which supposedly will detect the best settings that can be *reliably* run on your system.

After the nVidia software goes through it's paces... it suggested the following settings:

Core @ 563Mhz, Memory at 733Mhz :eek:

Thats a nice jump...

I'm off to see how stable it is...

More information if and when events warrant! :p
 

Lord Blackadder

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Apple has a reputation for underclocking video cards, and Tom's Hardware quotes the stock 7600GT (desktop) as 560MHz core / 700MHz memory, so you might not be overclocking the card, but rather restoring it to it's original Nvidia specs.

But that's not a bad thing - it means that your "overclock" will probably not effect the reliability of the card much if at all...but still provide a bump in performance!

Still, always be cautious when OC'ing an embedded video card. If it melts then it's new motherboard time. :(

Just keep an eye on GPU temperature and you should be OK. Good luck!
 

MacProGuy

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nagromme said:
Does that benefit OS X, or Windows, or both?

I hear you. I can tell you that the back of the case got reaaaaallly really warm, but nothing in the temp setting even approached what nVidia deemed as *dangerous* :)

But yes, something to watch... make sure we don't have a dead iMac because we wanted 8 more FPS in Quake 4 :rolleyes: :eek:

To answer nagromme... this is ONLY for Windows XP... there is, as of right now, no utility that I know of that will overclock these cards for OS X.

The utility you use in XP is actually an nVidia utility, not a 3rd party utility... so... who knows. Also, with the XP overclock, by default it resets itself to stock speeds upon reboot... I'm presuming to help avoid overheating if you've got it set too high :)
 

Flyinace2000

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Sep 28, 2004
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MacProGuy said:
I hear you. I can tell you that the back of the case got reaaaaallly really warm, but nothing in the temp setting even approached what nVidia deemed as *dangerous* :)

But yes, something to watch... make sure we don't have a dead iMac because we wanted 8 more FPS in Quake 4 :rolleyes: :eek:

To answer nagromme... this is ONLY for Windows XP... there is, as of right now, no utility that I know of that will overclock these cards for OS X.

The utility you use in XP is actually an nVidia utility, not a 3rd party utility... so... who knows. Also, with the XP overclock, by default it resets itself to stock speeds upon reboot... I'm presuming to help avoid overheating if you've got it set too high :)
THere is an application for OSX but its for ATI cards. Its called ATI Accelerator II. Works pretty well. Lets you OC on the fly.
 

Lord Blackadder

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Interesting - recently at the strangedogs video card flashing forum they have discovered that the Intel Mac cards have EFI firmware on their ROM but no BIOS. The BIOS for XP is stored somewhere else.

Future versions of ATIccelerator II may support both Nviia cards and Intel Macs cards (ATI & Nvidia), according to the developer.
 

capran

macrumors member
Nov 28, 2003
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MacProGuy said:
Ok... just thought I'd share...
...
Core @ 563Mhz, Memory at 733Mhz :eek:

Thats a nice jump...

I'm off to see how stable it is...

More information if and when events warrant! :p
Please post framerates for several games, before and after! :)

Also, see if the Nvidia utility (or a 3rd party one) will chart GPU temperature over time, so you can see what the highest temp is when running a game for an extended time.

Also, does the machine stay quiet when stressing like this? Or do(es) the fan(s) kick into overdrive?

PS: I'm anxious to know how Oblivion runs on this beast. On my gaming system, in order to get a consistent framerate that's always playable, I run at 840x525 with 2xAA (custom res made with Nvidia's driver), which is exactly 1/4 of my Dell 2005FPW's native res (to keep same aspect ratio.) Low-res but not too bad for this game. I'd like to know what your experiences are with the game on the 24".
 

Sesshi

macrumors G3
Jun 3, 2006
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If they do underclock, there has to be a reason for doing so. My (apparently repaired :rolleyes: ) MBP feels like it's going to melt and the case is hot enough to get burns off when stressing the GPU and the CPU at the same time.
 

Flyinace2000

macrumors 6502a
Sep 28, 2004
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capran said:
Please post framerates for several games, before and after! :)

Also, see if the Nvidia utility (or a 3rd party one) will chart GPU temperature over time, so you can see what the highest temp is when running a game for an extended time.

Also, does the machine stay quiet when stressing like this? Or do(es) the fan(s) kick into overdrive?

PS: I'm anxious to know how Oblivion runs on this beast. On my gaming system, in order to get a consistent framerate that's always playable, I run at 840x525 with 2xAA (custom res made with Nvidia's driver), which is exactly 1/4 of my Dell 2005FPW's native res (to keep same aspect ratio.) Low-res but not too bad for this game. I'd like to know what your experiences are with the game on the 24".
Here are my benchmarks for the system in my sig

http://forums.macrumors.com/showpost.php?p=2863025&postcount=24

CS2 and Lost Coast stress test: 60 and 61 fps
settings:
1902x1200 (16x10)
Model Detail High
Texture Detail High
Shader Detail High
Water Detail:Reflect World
Shadow Detail High
Color Correction Dissabled
Antialiasing mode: none
Filer mode: trilinear
Wait for Vert Sync: Disabled
HDR: Full
 

ZoomZoomZoom

macrumors 6502a
May 2, 2005
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So, for a game like WoW...

would it be better to run it in OS X, where you can't OC the nVidia card, but you can pass the bug that caps the FPS?

or...

better to run it in Windows, where you are capped at 64 (i think?) FPS, but because of the OC'd card, you'll have a higher minimum framerate?

Or does it not really matter, and running in either mode will yield great framerates? I use a lot of add-ons, and I do 40-man raids, so I am worried about the graphics card not being able to keep up.
 

Dont Hurt Me

macrumors 603
Dec 21, 2002
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A 7600Gt usually sits in a very large PC Box, Sitting in the back of the imac things could get pretty toasty. You may want to rethink this but apple does have a history running things a little lower. Clocking up is going to give you at best a few frames. Is that worth it? It maybe.;)
 

mrcammy

macrumors member
Sep 17, 2006
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I overclocked from 500/598 stock to 563/732 under XP. 3DMark06 went from 3031 to 3227 (for what it's worth).Temperatures were about the same.
 

Lord Blackadder

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Not sure if any of you guys have seen this, but Barefeats recently did some gaming benchmarks on the new iMacs and Mac Pro. He also discovered that the Radeon X1900XT in the Mac Pro has been downclocked by Apple, just like the iMac's GeForce 7600GT. :mad:

The results are pretty impressive for the 24" iMac, but all of the models did pretty well - the 7300GT is right up there with the X1600XT. It also shows how crap the Radeon X600 in the G5 iMac is. :(

The current crop of iMacs are all creditable gaming machines though. My only criticism is that they haven't made the GeForce 7600GT available in the cheaper models yet (and it would be nice to get it in the Mac Pro as an option). Still, since it is actually an upgradeable component there *might* be a kit available someday. Reminds me of the old mezzanine slot on the original Bondi iMac G3.
 

Spanky Deluxe

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Mar 17, 2005
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Lord Blackadder said:
Not sure if any of you guys have seen this, but Barefeats recently did some gaming benchmarks on the new iMacs and Mac Pro. He also discovered that the Radeon X1900XT in the Mac Pro has been downclocked by Apple, just like the iMac's GeForce 7600GT. :mad:

The results are pretty impressive for the 24" iMac, but all of the models did pretty well - the 7300GT is right up there with the X1600XT. It also shows how crap the Radeon X600 in the G5 iMac is. :(

The current crop of iMacs are all creditable gaming machines though. My only criticism is that they haven't made the GeForce 7600GT available in the cheaper models yet (and it would be nice to get it in the Mac Pro as an option). Still, since it is actually an upgradeable component there *might* be a kit available someday. Reminds me of the old mezzanine slot on the original Bondi iMac G3.
I believe only the 24" model has an upgradeable slot while the 1600 chips are soldered onto the boards of the 17 and 20" models. :(
 

Lord Blackadder

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Spanky Deluxe said:
I believe only the 24" model has an upgradeable slot while the 1600 chips are soldered onto the boards of the 17 and 20" models. :(
I hope you're wrong - that would be a bummer. If that is the case they should offer the 7600GT as a BTO option on at least the 20".
 

Spanky Deluxe

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Lord Blackadder said:
I hope you're wrong - that would be a bummer. If that is the case they should offer the 7600GT as a BTO option on at least the 20".
Future 20" iMacs could well have upgradeable graphics. I get the impression that the new Core 2 Duos are using the exact same logic board as the Core Duo 17 and 20 inch machines but with a faster core 2 duo chipped dropped into the cpu socket - no extra production costs. The 17" GMA950 model was already available as an educational model so no extra costs there. Only the 24" needed to be designed from new so that's the only one that they put the optional graphics in.
 

MacProGuy

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Original poster
Aug 16, 2006
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One thing you guys are forgetting is that there is almost NO WAY that overclocking the card, if done sensibly, can cause harm.

Why?

Because you can set a threshold in the nVidia software that allows you to specify at what TEMPERATURE the card will *scale back* it's overclocking to stock settings, alarms, etc.

So, as long as you set the threshold for something reasonable (say, what the current temp gets on FULL LOAD (i.e., under gaming stress) for say, 2 hours), then you really don't have anything to worry about.

:)
 

Lord Blackadder

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I don't think that works on the Mac - there isn't any "Nvidia software" that I'm aware of for the Mac that has those features. You can set the core/mem clocks in the ROM and that's it AFAIK.

Careful overclocking can yield good results, but you need to do it in stages - turn up the speed a little, run benchies/check temps, if it's still good turn it up a little more etc.

But each individual card has different overclocking potential, so there's no one "safe" overclock limit that applies to all cards in a given GPU class.
 

MacProGuy

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Lord Blackadder said:
I don't think that works on the Mac - there isn't any "Nvidia software" that I'm aware of for the Mac that has those features. You can set the core/mem clocks in the ROM and that's it AFAIK.

Careful overclocking can yield good results, but you need to do it in stages - turn up the speed a little, run benchies/check temps, if it's still good turn it up a little more etc.

But each individual card has different overclocking potential, so there's no one "safe" overclock limit that applies to all cards in a given GPU class.

Ahhh, yes... but I'm ONLY overclocking it in Windows... as a matter of fact, the overclocking on the Windows XP utility specified differences in 2D and 3D modes... so even though I've set it to be overclocked when I run games, it's ONLY overclocked while I'm playing 3D games... and once it gets back to the Windows desktop, it is no longer accellerated.

I wish nVidia would make such a feature of OSX... currently I am not overclocking in OSX, nor do I think I would without these safeguards in place... i.e., a ROM hack.
 

Lord Blackadder

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Unfortunately ROM hacking is the only way it has ever been done on the Mac.

MacProGuy said:
...as a matter of fact, the overclocking on the Windows XP utility specified differences in 2D and 3D modes... so even though I've set it to be overclocked when I run games, it's ONLY overclocked while I'm playing 3D games... and once it gets back to the Windows desktop, it is no longer accellerated.
From what I understand, OSX does not implement this feature because of Core Image - i.e. the video card is always doing 3D work even when you are just opening apps and documents. Thus they decided to be conservative with their clocks so that the card would be very unlikely to overheat from regular usage.

However, the Intel Macs may change a lot of this - I'm still waiting for the day when most PC video cards are dual platform compatible right out of the box. It could happen.
 

padré

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Aug 7, 2006
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X1900

Not sure if any of you guys have seen this, but Barefeats recently did some gaming benchmarks on the new iMacs and Mac Pro. He also discovered that the Radeon X1900XT in the Mac Pro has been downclocked by Apple, just like the iMac's GeForce 7600GT.
so euh, i'll be ordering my macpro this week, but when it gets here, do you guys have any good sites on how i should resolve the downclocking on the X1900 and bring it back to its original specs (i would only do that in windows)

thx
 

Lord Blackadder

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I'd try playing the games first and seeing if you are happy with the framerates you're getting - you might not need to overclock the card at all.

I believe Rivatuner can do overclocking, among other things.
 

nagromme

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May 2, 2002
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Agreed: unless you use really high FSAA (which is barely noticeable during play, vs. less FSAA) it seems like the iMac/7600 can run all current games quite well at 1920x1200.

Next-gen games like UT2007 may need some fiddling to achieve usable performance, but they may be nothing worth improving for now :)
 

MacProGuy

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nagromme said:
Agreed: unless you use really high FSAA (which is barely noticeable during play, vs. less FSAA) it seems like the iMac/7600 can run all current games quite well at 1920x1200.

Next-gen games like UT2007 may need some fiddling to achieve usable performance, but they may be nothing worth improving for now :)

Agreed X2.

Actually, I was using previously a Windows XP Gaming Machine with a 19" Monitor (1280x1024)...

And to my eye... the games look better at 1920x1200 with no FSAA or 2x FSAA than they did on my 1280x1024 at 8xFSAA...

So... I have NO problems running WITHOUT much FSAA as I know I have such a high resolution on the monitor at 50+ FPS on basically anything I throw at it :)