Jump to content
OGXbox.com

Theoretical Gpu Overclock


neighbor
 Share

Recommended Posts

Hello folks, we all know the XGPU is sort of cousin to Geforce 3 and Ti200, Ti500. Just found a tutorial on how to overclock the Geforce 3 series, basically it is about increasing voltage on the GPU core and RAM chips, by adding resistors to so called voltage controllers. The voltage controllers on the Geforce 3 series are SC1175CSW, similar controllers are on the Xbox too. One located unde the CPU, named SC1186CSW (PII, PIII voltage controller). And another one SC1110CS (voltage controller for DDR memory) located near the GAME1/2 connector.

Need help of guys who know electronics, regarding how to apply same resistor mod to the Xbox RAM voltage controller. so the voltage between RAM chip's VDD contact and GND - will increase higher than stock tension of 3.06 volts.

notes:

- Geforce 3 have 2 x SC1175CSW , Xbox has one SC1110CS which fits the description

- Xbox 1.0 motherboard was researched for this purpose, other motherboard revisions don't have SC1110CS

- there was info on the web about a prototype Xbox motherboard which had a switch to overclock the GPU

- Xbox 1.0 motherboard has GPU fan, other revisions don't have

- my speculation is: one of voltage controllers located on Xbox motherboard feeds the GPU, it may be the one under CPU, because there is only 1 voltage controller of that kind in other Xbox revisions, only 1.0 has 2 of them, under CPU and near GAME1/2 connector.

 

links:

overclocking Geforce 3

overclocking Geforce 3 Ti200/Ti500

SC1175CSW - Geforce 3 voltage controller

SC1110CS - Xbox RAM voltage controller

K4D263238F-QC50 - Xbox RAM chips

potential GPU overclock.png

Edited by neighbor
Link to comment
Share on other sites

So, I've done this, connected a potentiometter between Vcc and OCSET, gone from 1000ohm down to 50ohm, the Xbox powering on, but shown no picture on the screen, and there was kind of clicking noise going from motherboard. Between VDD and VSS(gnd) on RAM chips, still 3.06volts. So no boot and no voltage increase. Any thoughts?

OCSET Xbox RAM voltage controller overcurrent.jpg

ocset pin.jpg

After removing the potentiometer, everything was fine.

Edited by neighbor
Link to comment
Share on other sites

The problem I see is that the RAM on the Xbox is shared between the CPU and the GPU.  

The mod you show is for a separate graphics card plugged into a slot on a PC motherboard.  No memory shared between the CPU and GPU. 

Is the voltage level to power the GPU separate from the CPU of the Xbox?

Also, I'm not sure that just changing the voltage level alone will change the GPU speed.  Other settings in configuration registers of the GPU would have to be modified and or the clock circuitry that drives the GPU.

  • Like 1
Link to comment
Share on other sites

I dont think Vcc/OCSET is right.

Vout is appears to be set by the R4/R5 voltage divider in the SC1110 circuit providing a reference to the REFin pin.

With reference to the example circuit from the datasheet 1k/1k is a ratio of 0.5. Vout = 0.5 x Vin = 1.25V. If you put a resistor in parallel of R4 you could increase the voltage but be cautious or you will fry something. There's probably more to it, but my 1 minute skim of the datasheet. 

In anycase I think @KaosEngineer is right. Changing just the voltage wont achieve much. Best to work out how to change the clock speed first.

Edited by Ryzee119
  • Like 1
Link to comment
Share on other sites

53 minutes ago, Kekule said:

have you played around with this:

https://github.com/WulfyStylez/XBOverclock

How come this did not blow up yet?
never heard of this, will try to compile, never actually did it, and check if it does something. But the guy says he achieved:

259MHz NVCLK, 141MHz FSB.

 

Edited by neighbor
Link to comment
Share on other sites

2 hours ago, neighbor said:

How come this did not blow up yet?
never heard of this, will try to compile, never actually did it, and check if it does something. But the guy says he achieved:


259MHz NVCLK, 141MHz FSB.

 

I havent played with it yet.... like he said, if you pick a bad value you wont even boot... that its a rather new repo.... I plan on compiling it at some point

  • Like 1
Link to comment
Share on other sites

7 hours ago, Kekule said:

if you pick a bad value you wont even boot

not a problem if the bios goes to a modchip and the board TSOP already has a IND bios. So if it's not booting, then remove the modchip, boot, put the modchip back and flash it with new bios. If this thing really works, overclocking the GPU would make a lot of 720p hex patched games to run fullspeed.

  • Like 1
Link to comment
Share on other sites

2 hours ago, KaosEngineer said:

From the content of the Makefile, it looks like the development environment to compile the code is Linux, not Windows.

if you look at the code he has defines for _Win32 so Im sure if you had gcc set up right it would work.

I can confirm it compiles file with mingw

xboverclock.PNG

Edited by Kekule
  • Like 1
Link to comment
Share on other sites

28 minutes ago, KaosEngineer said:

nice, no voltage regulator changes.  

I've clocked the GPU to 315mhz (stock 233mhz), there is noticeable increase in fps on Halo CE in 720p, but still a lot of explosions or too much reflections are making framedrops. So maybe voltage increase will help the GPU. Also do you know if Xbox supports K4D263238F-QC40 chips, because their top speed is 250mhz compared to 200mhz of K4D263238F-QC50

  • Like 1
Link to comment
Share on other sites

With the overclocking tool, I managed to get 280mhz on the gpu and 158.3mhz fsb which is 1660mhz on the cpu (I did both overclocks at the same time). I couldn't push any higher on the cpu and I know the gpu at 290, the xbox freezes up on boot. My xbox is a v1.1 with the x3cp mod with the 1.4ghz cpu replacement and the 128mb ram upgrade. 

So far the only thing I tested was Goldeneye on N64 emulator and the game so far at the start, there is almost no performance hit with 720p with the overclocks. I'll test some more stuff if anybody wants to know the performance of any other emulators or whatever. Maybe I'll test my other 1.4ghz xbox which is a v1.4 with that different gpu and see what I'd get.

 

 

20190325_232521.jpg

Edited by y0urh34d
  • Like 3
Link to comment
Share on other sites

1 hour ago, y0urh34d said:

With the overclocking tool, I managed to get 280mhz on the gpu and 158.3mhz fsb which is 1660mhz on the cpu (I did both overclocks at the same time). I couldn't push any higher on the cpu and I know the gpu at 290, the xbox freezes up on boot. My xbox is a v1.1 with the x3cp mod with the 1.4ghz cpu replacement and the 128mb ram upgrade. 

So far the only thing I tested was Goldeneye on N64 emulator and the game so far at the start, there is almost no performance hit with 720p with the overclocks. I'll test some more stuff if anybody wants to know the performance of any other emulators or whatever. Maybe I'll test my other 1.4ghz xbox which is a v1.4 with that different gpu and see what I'd get.

nice, did you add more cooling to the board?
did you patch the xbe for new 1660mhz speed?

did you try to watch 720p mp4 videos?

did you try GTAIII in 720p with the trails effect off?
 

Edited by neighbor
  • Like 1
Link to comment
Share on other sites

36 minutes ago, neighbor said:

bud, did you succeed to patch GTA SA and GTA VC for 720p?

I couldn't overcome the double screen on Gta Vc, for anyone interested whats happening is the game is running at 720x720 not 1280x720 so you get the double screen, I found it in 3 but not vc. Gta sa would black screen no matter what and its outside my basic understanding of hexing an xbe.

 

Im just about to start work so I'll get back to testing the stuff you want to know when I get home.Also for the cooling, I have whatever heatsink N64 Freak chucked on the cpu but I'm certain he kept the gpu cooler stock.

Edited by y0urh34d
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

Board Life Status


Board startup date: April 23, 2017 12:45:48
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.