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7900 GS factory settings vs. o/c settings

post #1 of 25
12/11/06 at 1:18pm
Thread Starter 
Hi,

I have the 9400 with the 7900 GS.
I read from these forums that people o/c their 7900 in average to something around 600/1100.
Coolbit says my factory settings are 375/507 and recommends o/c to 404/571.
That's HALF of what people get in this thread : http://www.notebookforums.com/thread157393.html

However, this site about mobile GPU (http://www.killernotebooks.com/suppo...bile_gpus.aspx) confirms the 7900 GS is factory clocked at 375/500.

I must be missing a part. Can anybody clarify please ?

Thanks.
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post #2 of 25
12/11/06 at 3:37pm
No all the DELL 7900GS are essentially similarly clocked however you probably didnt read over the thread since there is specific instructions on getting high clock speeds. Head over to the VIDEO CARD FAQ sticky and sit down and read it through you will find all the information you need.

http://www.notebookforums.com/thread180011.html
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post #3 of 25
12/11/06 at 3:44pm
Also you can't use coolbits to overclock your video card. Dell locks the bios and you must flash the video cards bios with custom clock settings and for some who have really good temps, extra volts to get higher speeds. Please if you don't understand anything of what I just said, don't do it. The 7900GS is a great card even at stock speeds. You can damage or flash the wrong bios which would means you would need dell to fix you laptop. Also by doing this you are voiding your warrenty.
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post #4 of 25
12/11/06 at 4:04pm
Thread Starter 
Hi,I didn't explain myself well. First of all the essence of my question was how come my factory settings says 375/500 and from these forums people say their factory settings are 375/1000. Why 1000 ? Is it understood that on this card the memory bandwidth is calculated with a X2 multiplier? That's the part I missed.
Also, lots of people push their core speed up to 550-600. That's very far from the 375 factory settings, wouldn't you say ? Is it because of the voltage that the card can handle it, or is it this much underclocked stock ?

Quote:
Originally Posted by vengance_01
Also you can't use coolbits to overclock your video card..

I know I can't o/c from software. However, One How to Guide says to use Coolbit to test for a safe overclocking range. That's a wize start.
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post #5 of 25
12/11/06 at 4:07pm
Thread Starter 
Quote:
Originally Posted by DELL-Machina
No all the DELL 7900GS are essentially similarly clocked however you probably didnt read over the thread since there is specific instructions on getting high clock speeds. Head over to the VIDEO CARD FAQ sticky and sit down and read it through you will find all the information you need.

http://www.notebookforums.com/thread180011.html

That's exactly what I did before opening up a new thread with this question. It was awkardly formulated though. I just gave it a second try
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post #6 of 25
12/11/06 at 6:25pm
375/500, or 375/1000 is the same thing, for now. The memory is DDR2, so it runs at 500, but its effectively doubled due to the DDR2.

The card is insanely underclocked, and im willing to bet the only reason they did so was because of temperature. Most 7900 GS will run at 600/800 with the GTX bios and 1.24v, but temps really get high, like high 80's low 90's. Still not pushing 78xx temps, but a little high for my taste with the single pipe heat sync. To combat this, you can overclock it and over volt it to 1.24v, then start backing off on the voltages to have it run cooler. I know KraziePop has his successfully running at 1.05v (nuts) at 600/800 i believe with temps in the low to mid 80s if im not mistaken.

The GTX runs at 1.24v, but has a dual pipe heat sync. Another reason they OC so well is that they are built on a 90nm process which enabled them to run very cool, so you can voltmod them and clock them higher.
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post #7 of 25
12/11/06 at 6:36pm
Thread Starter 
Thanks nissanztt90 for clarifying !
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post #8 of 25
12/11/06 at 7:48pm
No problem.
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post #9 of 25
12/11/06 at 8:33pm
I also used Krayziepop's rom on my GS and everything runs fine @ 600/800/1.05v for me as well. It seem as if the 7900 GS is a very energy efficient card when using the 7900 GTX bios, and that 1.24v is absolute overkill for it.
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post #10 of 25
12/12/06 at 5:59am
The reasons people are getting higher clock speeds by flashing to the "GSX" BIOS (a modified 7900 GTX BIOS) is because of 2 things...

1.) For the GPU Core, higher voltages are applied to the core, which, as a general rule, fosters higher clock speeds. This is why people can generally push their Core to higher clock speeds.

2.) For the Memory, with the "GSX" (modified 7900 GTX) BIOS, the memory has relaxed (i.e. less restrictive) memory timings, which allows for higher clock speeds. It's the same for system RAM. When overclocking, if you're going to push your memory to a higher clockspeed as a result of CPU/RAM dividers, a good rule of thumb is to relax memory timings (i.e. raise them from, say 2.5-3-3-8 to, say, 3.0-4-4-12). This is essentially the same thing that's done with the different BIOSes. The "standard" 7900 GS BIOS has "tighter" (lower) memory timings, while the 7900 GTX BIOS has "looser" (higher) memory timings, which, again, allow for higher clock speeds.


Long winded, I know, but I hope it clears things up a bit .


EDIT: Also, the reason you see the clock speeds of the 7900 GS reported as both 375\500 and 375\1000 is because the memory the 7900 GS uses is DDR memory. Some people report the "effective" speed of the RAM as double the real clock speed. The reason for this is because normal SDRAM memory transmits 1 piece of data per clock cycle, while DDR-SDRAM memory transmits 2 pieces of data per clock cycle. So, DDR memory running at 500MHz can transmit as much data "per second" (which is the measuring factor, usually in GB per second) as SDRAM memory running at 1000MHz, provided the memory bus width is the same (in the 7900 GS's case, 256-bit). It's just a personal preference on how DDR is reported .
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post #11 of 25
12/12/06 at 4:11pm
I wonder why then does the 7900 GTX memory clock reach its peak so much lower than the GSX?
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post #12 of 25
12/12/06 at 9:42pm
The "GSX" BIOS is a MODIFIED 7900 GTX BIOS. I haven't actually looked at the "GSX" BIOS, but if I were to make an educated guess, I would say that the "GSX" BIOS has slightly higher GPU Core voltages (maybe), as well as higher (i.e. more relaxed) memory timings. This would allow for higher core and memory clock speeds .
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post #13 of 25
12/12/06 at 10:15pm
Ah. I think i might try flashing to the GSX bios to see if i can get some higher memory clocks then.
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post #14 of 25
12/12/06 at 10:31pm
Quote:
Originally Posted by nissanztt90
I wonder why then does the 7900 GTX memory clock reach its peak so much lower than the GSX?
Well mine is running 700Mhz and I've pushed it to 725 without exceeding 83 Degrees during stress tests so I don't know that that's a lot lower; the reason I say this is because I think the GTX uses GDDR3 memory instead of GDDR2 which means it is a different memory architecture. Here's a bit from the Wiki...

Quote:
Originally Posted by Wiki
The GDDR offshoot
The first commercial product to claim using the "DDR2" technology was the NVIDIA GeForce FX 5800 graphics card. However, it is important to note that this GDDR-2 memory used on graphics cards such as the GeForce FX 5800 is not DDR2 per se but rather an early midpoint of DDR and DDR2 technologies. Using "DDR2" to refer to GDDR-2 is a colloquial misnomer. In particular, the performance-enhancing doubling of the I/O clock rate is missing. It had severe overheating issues due to the nominal DDR voltages. ATI has since designed the GDDR technology further, into GDDR3, which is more true to the DDR2 specifications, though with several additions suited for graphics cards.

After GDDR2's introduction with the FX 5800 series, the 5900 and 5950 series reverted to DDR, but NVIDIA's old mainstream card, the 5700 Ultra, used GDDR2 clocked at 450 MHz (compared to 400 MHz on the regular 5800 or 500 MHz on the 5800 Ultra).


ATI Technologies's Radeon 9800 Pro with 256 MiB memory (not the 128 MiB version) also used GDDR2, but this was because it required fewer pins than DDR. The Radeon 9800 Pro 256 MiB only runs its memory at 20 MHz faster than the 128 MiB version, and primarily to counter the performance hit caused by higher latency and the increased number of chips. It is speculated that the GDDR2 used on ATI's 9800 Pro 256 MiB was actually supposed to be used on the GeForce FX 5800 series, but ended up unused after NVIDIA decided to halt the 5800 line's production. The 9800XT that followed reverted to DDR, and later on ATI began to use GDDR3 memory on their Radeon X800 line.

GDDR3 is now commonly used in most NVIDIA- or ATI-based video cards. However, further confusion has been added to the mix with the appearance of budget and mid-range graphics cards which claim to use "DDR2". These cards actually use standard DDR2 chips designed for use as main system memory. These chips cannot achieve the speeds that GDDR3 can but are fast and cheap enough to be used as memory on mid-range cards.

http://en.wikipedia.org/wiki/DDR2_SDRAM

Here's the one about GDDR3

http://en.wikipedia.org/wiki/GDDR3

Anyway I'm just saying I don't know that you can compare clock for clock the memory if it's GDDR3 vs DDR2...
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post #15 of 25
12/12/06 at 11:15pm
Im fairly certain they both utilize gddr3.

http://www.pcper.com/article.php?aid=237

Second table down.

I can clock mine to 725, but thats pushing the bleeding edge of stability. COH does some funny things when loading but plays ok, where as any higher and it would crash.
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post #16 of 25
12/12/06 at 11:20pm
Both cards utilize GDDR3.
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post #17 of 25
12/13/06 at 2:10am
Yes, they both utilize GDDR3 guys. On top of that, the 7900GS/GTX both have the exact same memory timings. The 'GSX' BIOS is nothing but a special tag for a GTX BIOS. There is nothing different, only clockspeeds. Personally I wish there was a difference in memory timings, as that would explain why a GS with the GTX BIOS can clock up the memory so dang high. This is just simply not the case, however. Another thing to keep in mind guys, when you are talking about voltage on these cards, that means CORE voltage. So no matter where you set the voltage at on your 7900, the memory won't benefit or suffer from it. This also implies that running higher memory clockspeeds will not significantly change the temps you see in the NV Control Panel. The temp probe is built into the core, so we have no way of telling what our memory temps are. Also both cards are very CORE limited in 3D apps, i.e- higher core clocks will gain you MUCH better FPS than higher MEM clocks can.

Hope this cleared up some things for you guys.
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post #18 of 25
12/14/06 at 3:20am
Quote:
Originally Posted by nissanztt90
Im fairly certain they both utilize gddr3.

http://www.pcper.com/article.php?aid=237

Second table down.

I can clock mine to 725, but thats pushing the bleeding edge of stability. COH does some funny things when loading but plays ok, where as any higher and it would crash.
I stand corrected; sorry for the oversight.
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post #19 of 25
12/14/06 at 10:51am
Thread Starter 
Quote:
Originally Posted by nissanztt90
Ah. I think i might try flashing to the GSX bios to see if i can get some higher memory clocks then.

I'm using the GSX BIOS and 725 is the maximum I can get without seeing artifacts. At 775 it would become unstable with artifcacts in ATI Tool and 3DMArk. I'm running at 1.24v, and I'm not very satisfied with my temps. ATITool, after 10 minutes, raises the temps to 87. I'd rather keep it in the lower 80. Idle temps are good though, since the GSX is set to 0.9v by default in 2D.

I'll try this Krazipop BIOS you're talking about to lower my temps oin 3D and see if it helps.
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post #20 of 25
12/14/06 at 3:19pm
You may just have a card that cannot hit higher mem clocks. Ensure your not also going way over on your core speed clocks either since core speeds effect temps more than the mem speeds.
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