Hey guys I thought I would write a very simple guide for people new to over clocking their graphics processing unit (GPU), focusing on the new ATi Radeon HD 4850 as it is a mid to high range card with a mid to low range price and would most suite a first time builder/ over clocker. So here goes, will add some pictures later, I'm at work right now.

Step 1 - Hardware Installation:

So this may seem like a simple process but with some added thought you can squeeze a little more stability and clock speed out of your GPU just through clever installation.

1.a

NA Computer - Naturally Aspirated i.e A computer set up with stock fans in the case and maybe a few fans purchased along with it. When installing the GPU in the PCIe slot on your motherboard you will notice there are two slots, the second sitting lower and the first which sits a little bit higher. My advice is that airflow in your case is the most important thing, and so cable management and fan positioning is also important.

_______________________________________________
| | | |
| PSU | | HDD |
| | | |
|...................| |...........................|
| |
| |
|------------------------------------------| |
| ========== <-- PCIe 1 | |
| | |
| ========== <-- PCIe 2 | |
|.....................................................| ...................|
| | |
| | HDD |
|_____________________________________|_________ |
Fig.1

3 Key Airflow Positions
---------------------------

Above in this really poorly made drawing, hey I make computers I'm no artist, you can see the two HDD bays aka Hard drive bays, where the hard drives are installed and also the PSU aka power supply unit. Some case designs will vary but fundamentally this is the layout of the inside of most cases, and the key to good airflow and good over clocking starts here.

Heat rises and so should your computer's heat flow, positioning some fans in front of the HDD is an optimal position to move hot air that lays dormant in the case leading to higher ambient temperatures. Also if you move most of your cables and store them in the top HDD bay in the front, or behind the left hand side panel, it leaves a greater open area for air to flow freely.

_______________________________________________
| | | |
| PSU |=+=+=+=+=+=+=+=+=+=+| HDD | | Cable to HDD = | |
|...................| & Motherboard + |...........................|
| = + |
| + += |
|------------------------------------------| = + |
| ========== <-- PCIe 1 | = |
| |=+= +=+ |
| ========== <-- PCIe 2 | |
|.....................................................| ...................|
| | |
| | HDD |
|_____________________________________|_________ |
Fig.2

As I have tried to show again in Fig.2, by moving the cables as far away from the CPU and GPU and storing them to the upper front side of the case you can leave the bottom area relatively free for airflow over the main components. Behind the PSU at the top left and the middle of the top of the case will usually have fans which suck the air out of the case. It all depends on the case you make or buy of course, however the fans blowing air into the case are usually located behind the motherboard to the left, next to the I/O shield where you plug in USB components and sound card components etc. As well as the bottom left near the second HDD bay.

Arranging cables and checking airflow before installing components will probably save you most of the heat build up in your case and allow for a good over clock with no expense added, just a little time and effort. Besides that it makes you appreciate the work you have done and looks great.

Aftermarket Fans for the GPU:
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The drilled holes in the Ati Radeon HD 4850 line up exactly with previous generation 3000 series and so most heat sinks and after market fans are applicable in this case. If you are seriously wanting the most out of your card then an after market fan is the second best choice after water cooling it, with the third being a rough mod of the fan which I will explain later.

If you decide to buy a heat sink make sure you get an additional fan to move the heat from the heat sink and help it get up and out of the case, heat sinks are great for spreading heat but not at moving it out of the case so please keep that in mind. I am not mentioning brands in here because that is up to the user's discretion but anything over $40 should work fine and generally go with a company that makes fans and or heat sinks as their main purpose, quality of product is generally better.

Taking apart the Ati Radeon HD 4850:
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You are probably thinking, if you haven't done this before, damn I just spent alot of money on this nice card, do I really won't to open it up? What if I break something, on the package it says "work at an anti-static bench/ workstation" What is that and what happens if I touch the circuitry on the GPU will it break?

Ok, just relax and go clean your hands, put down the mountain dew and doritos and go clean those filthy digits.

Now your hands are all clean and dry take the card out of the dark gray anti-static package and lay the gray packaging on top of a stable table or bench. You now have a ghetto anti-static bench!

Take some time to look at your card, see what is on it, lots of shiny copper things and some things called screws which are on the back of the card. These are what we are interested in right now, if you flip the card over there should be about 4 screws which are attached to a square metal bracket. Under the metal bracket are some pieces of foam so the bracket doesn't scratch or touch the circuit board.

Step 1. Unscrew the four screws at the back of the card, they have springs around them and won't fall out when completely unscrewed, you will have to pry the bracket off gently so the foam padding comes away from the card.

Step 2. Turn the card over again and unscrew the 8 or so screws, basically every screw you can see. The fan and heat sink will then come off quite easily.

Step 3. You're done, your card is now naked and ready to be dressed in it's new fan or heat combination. Just follow the instructions of the fan or heat sink you purchased and should you have any problems write a message down below, I will help you out.

Modding the Stock Fan AKA Ghetto Cooling:
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For now the fans don't really push themselves much over the 25% fan speed and as such cause the card to get too hot for comfort and more importantly for over clocking. So as a temporary mod you can disable the cable that limits the fan speed by removing one of the wires.

This wire can be removed and replaced without cutting, the wire is the BLUE one.

Remove the wire after taking apart the heat sink and opening up where it goes into, remember this is only if you can't afford an extra $10-40 for a proper replacement solution! If you google there are plenty of articles on how to do this. -----> http://www.google.com is your friend!

Temperature Monitoring:
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http://www.cpuid.com/hwmonitor.php

http://www.almico.com/speedfan.php

http://www.lavalys.com/products/do [...] UE&lang=en

These three sites offer freeware tempreture monitoring software, which also monitors your fans RPM (fan speed), voltages and a few other things related to heat build up in your system.


Enough talk, over clock me baby!
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After installing the software that came with your package, you should download the Hotfix for the 4850 which fixes some issues with early drivers loaded straight onto the installation disc.

Hot fix
--------

XP Users for both 32 bit and 64 bit
https://a248.e.akamai.net/f/674/920 [...] _64899.exe

Vista Users for both 32 bit and 64 bit
https://a248.e.akamai.net/f/674/920 [...] _64906.exe

Over clock using ATi Overdrive:
-------------------------------------

I am at work and couldn't get a picture loaded up in time so I will link you to a site which has a picture of the screen I am talking about and some more details on their over clocking experience (They only managed 700MHz Core clock and 1050 on their Memory clock speed.)
http://en.expreview.com/2008/06/24 [...] hd-4850/6/

Ok so looking at that picture on the left, you can see a golden padlock, just under the graphics card adapter selection bar. Click it once to unlock it giving you access to the slider down below.

The top slider is your GPU's core clock and the bottom is the memory clock speed controllers.

Below that you have Result with a blank box and to the right of it you have Accept and Restore. these tools are in place so that if you over clock too far and it fails to pass the test, you can reset it to the last working clock speed in a single click of a button. Quite easy to use really!

Adjusting Clock Speeds:
----------------------------

When I over clocked my ATi Radeon HD 4850, I had a Thermaltake Duo Orb on the card with a water cooled system for my CPU. I managed 700MHz GPU clock and 1085MHz Memory Clock, so this is technically on air and not a water cooling solution for the GPU. Keeping in mind 1100MHz is the max for memory clock I think this is a more than decent result, if I don't say so myself.

I started by maxing out the GPU clock to 700MHz and then moving the memory clock to 1050MHz, you may wish to start lower on the memory clock if you have stock cooling, try working up from 1000MHz in 5MHz increments.

Adjust it each time adding 5MHz to the clock and hitting test, if it comes back as Passed you are set to try another 5MHz. When you reach a Failed conclusion to your test, hit restore and then accept and you have reached your maximum over clock!

Final Thoughts:
------------------

I am no pro at over clocking, I studied alot of articles about cooling, wire management and over clocking and now I am trying to give something back to the people just new to this type of thing. The easiest thing about over clocking the ATi Radeon HD 4850 was the over clocking itself, after installing the after market cooler it was all downhill from there. If you follow the above guide and have any suggestions for it please add a comment below, thank you for reading and I hope this helps even one person answer that last little question in their head they had before trying to do this type of thing.

Enjoy and Over clock to the limit!

A really good Guide. One of the best I have read here. Good Job.

It's a pretty good guide for people completely new to working with computers. It looks like you put a lot of work into it.

There are auto overclock features in catalyst control center BTW. It'll overclock for you, if it hangs or crashes, it'll pick right off where it left off on reboot.

Love the diagrams. You need to discover www.text-image.com for all your ASCII art needs Should just upload a gif diagram to photobucket and post that.

We should have a sticky thread on this forum with guides like this, about how to do things or how things work.

Ok I updated the post, didn't put pictures in because I am about to format my computer and do a fresh install.

I updated the hotfix links and gave direct driver download links for vista and xp 32 bit and 64 bit users.

You clearly put a lot of time into this.

I have found in my experience that you will get a much higher over clock doing things manually. The "Auto Tune" program in the top right hand corner of Catalyst Control Centre is only if you don't know how to click the golden padlock, which I don't think many people will have trouble doing if they read the above guide.

Along with sufficient cooling this guide can be applied to the 4870 as well of course, and is only written with beginners in mind or some reassurance for people over clocking from someone who has done it already.

Hope you enjoyed it!

So I am in the process of selecting the components of my rig and I have decided to get 2x HD4850 in CF(brand - ASUS).I have decided to buy the Thermaltake DuOrb as my aftermarket cooler.Along with it would these ramsinks be good enough?-
http://www.newegg.com/Product/Prod [...] 6835118220

excellent guide, i'll try it when i get my 4870x2! *drool*

I just hit 1100 MHz memory clock, reportedly stable, with ATi overdrive and the stock cooler.

I'm curious as to what differences it will make while gaming : D

That was actually my first attempt at overclocking anything, hah. I'm happy they made it so easy.

Very nice guide that a lot of time was spent on but a couple of observations...

1. BIOS flashing is REALLY easy these days with RBE and ATIWinFlash. Then the stock cooler fan speed can be adjusted without risking damage by changing to an aftermarket cooler. Just something that should be mentioned with a link to the many how-to guides out there. ALSO there is a way of saving a profile in CCC that alows you to up the fan speed. This is an even easier way to help with your fan speed/cooling. The stock cooler becomes very "servicable" at this point. Personally I flashed my Visiontek card to be an Asus and used the Asus software to control the fan speed. After much experimentation, the AUTO setting works incredibly well with the fan at 41% most of the time and scaling upwards with temp from there.

2. The auto-tune overclocking feature in CCC actually does a FINE job of finding the limits of your card. i was pleasantly surprised. I had to actually back mine down a bit to avoid occasional artifacts.

3. The memory limit is NOT 1100 but at least 1200. Mine hits 1125 no problem.

Have fun guys! Just my $.02 on my personal findings with one of the very best bang for the buck cards ever!

The auto overclock sucks it put it way to hi for me and it crashed once i started a stupid game