# A few things about GPU overclocking I want to clarify.



## GetOutOfBox (Oct 17, 2008)

I've been overclocking hardware for a long time, but I always operated under the following assumptions, since they're are assumptions, I'd like to clarify them, I havn't broken anything yet, but I don't want to in the future, since I don't have unlimited money (hack please? 

Assumptions:

1. Overclocking will only damage the component (CPU/GPU) if the temperate rises over Thermal Design Limits, or you increase the voltage enough to literally fry it.

2. Simply raising the clock rate without touching voltages will NOT damage the component unless it's temps rise above design limits.

So what I'm asking is, can you still damage a component just by raising the clock rates (without changing voltages), but its still well under max temp? For example, say I raised my GPU's core clock 100 mhz (total 665 to 765 mhz) (gradually, like normal OC technique dictates), did not touch the voltages, and the temperate was 60C and under pressure (FurMark Stability Test/Crysis), could it just suddenly die, without the temp rising?

My impression was that the most that can happen when simply raising the clock rate (assuming the temp doesn't skyrocket) is the component refusing to start, forcing you to reset to default clock rates. Is this correct?

EDIT: FYI the GPU I'm talking about is a Radeon 4850, 1GB VRAM


----------



## greenbrucelee (Apr 24, 2007)

GetOutOfBox said:


> I've been overclocking hardware for a long time, but I always operated under the following assumptions, since they're are assumptions, I'd like to clarify them, I havn't broken anything yet, but I don't want to in the future, since I don't have unlimited money (hack please?
> 
> Assumptions:
> 
> ...


1 Yes you are correct.
2 Yes you are correct.

It is the same with overclocking a cpu, I managed hit to 4GHz with my cpu without raising the vcore but I raised the vcore anyway just to give it room to breath.

If you start breaking the temp threshold of any component even if you havent raise the voltage it will get damaged.

Changing the main settings will create a smaller life span than normal settings would but it should not cause the card to suddenly die on you but you need to take things carefully as with any overclocking such as do you have a good power supply, do you have good cooling, do you have good airflow. If yes is the answer to all those questions then instead of a 10 year life span for your card it may have 8 and you will probably have upgraded to a better one long before then.


----------



## GetOutOfBox (Oct 17, 2008)

Ok thanks, now I have a problem.

I overclocked my Radeon 4850's core clock to 775mhz, stable, average temperature while running an XtremeBurn Furmark Stability test is 60C.

For some reason, I can't seem to overclock the memory clock at all. I add even 15 mhz and artifacts start appearing.

I have this cooler: http://www.newegg.ca/Product/Product.aspx?Item=N82E16835118037

It's great keeps everything cool, it even came with little heatsinks for the RAM, which my card didn't have. When not overclocked, RAM temps stay under 55C when under load. I don't see why they can't go up even a little, when core clock can be raised 115mhz. Also, whenever I try to set them in ATI Tray Tools, when I click apply, it actually sets them either a few mhz under or above what I entered to be set. 

It's kind of like how some DVD writers experience a "Write speed mismatch", where the user selected 4x as the speed, but the drive firmware told the drive to write 8x, due to a bug.


----------



## greenbrucelee (Apr 24, 2007)

your link didn't work.

Overclocking anything can be affected by anything else. Try setting the PCIe frequency manually to 100 in the BIOS and dont leave it on auto.


----------



## GetOutOfBox (Oct 17, 2008)

link works fine for me, downforeveryoneorjustme.com reports its working fine

could the problem be caused by the 8x slot the cards running in? I had to use the slot farthest from my sound card to avoid popping in the sound.


----------



## greenbrucelee (Apr 24, 2007)

yeah, shouldn't it be in x16 slot?


----------



## MonsterMiata (Jan 5, 2010)

Use riva tuner instead off CCC, its junk and there are known issues with it. I leave it uninstalled. I would also suggest GPU-z for monitoring your temps. There are also some issues with the new drivers as well if your using them.


----------



## GetOutOfBox (Oct 17, 2008)

I didn't use CCC, I used ATI Tray Tool's to overclock (not using Overdrive).

and yes it would optimally be in a x16 slot, but performance comparisons show only a 4-7% bandwidth performance decrease between 8x and 16x due to most cards not using anywhere near the full bandwidth of x16. So since my video card almost touches my sound card (X-Fi Titanium) when its in the first PCI-E slot (which causes popping and distortion in audio output due to EMI, ElectroMagnetic Interference), I put it in the second PCI-E slot.

FYI I remember having trouble overclocking the memory on the same card with my old mobo, and that time it was definitely in the x16 slot. Is it just that the radeon 4850 is **** when it comes to overclocking?

EDIT: Just tried to play Oblivion with the 'stable' core clock (left memory at default), and it crashed upon loading the Tamriel Worldspace. (Basically, the rendering engine failed to initialize). The core clock produced no artifacts in ATI Tray Tool's artifact testing feature (uses algorithms to auto-detect artifacting, I suspect with the help of checksums or something).

So basically, this card isn't OCing at all. It will appear stable when overclocking the core, but once you load a game that stresses it even a little, it just freezes. It's not undervolted, I checked in the Overclock settings page in ATT, its set to 1.158 volts (maximum stock voltage, I'm not risking my card with a volt mod).

Temperatures are great, even when overclocked, it stays in the 50C range in stress testing.


----------



## GetOutOfBox (Oct 17, 2008)

Should I try overvolting the card just a little (using a BIOS mod, not a hardware mod)? Like from 1.158 to 1.26? The 4870 which is just a tad faster runs at 1.26.


----------



## greenbrucelee (Apr 24, 2007)

set the pcie frequency in the bios manually to 100 and see what happens.


----------



## MonsterMiata (Jan 5, 2010)

GetOutOfBox said:


> I didn't use CCC, I used ATI Tray Tool's to overclock (not using Overdrive).
> 
> and yes it would optimally be in a x16 slot, but performance comparisons show only a 4-7% bandwidth performance decrease between 8x and 16x due to most cards not using anywhere near the full bandwidth of x16. So since my video card almost touches my sound card (X-Fi Titanium) when its in the first PCI-E slot (which causes popping and distortion in audio output due to EMI, ElectroMagnetic Interference), I put it in the second PCI-E slot.
> 
> ...


Have you tried a different OCing tool to see what results you get? The 4850 is not a bad OCer. Temps will be the limiting factor which yours sound fine. You might have a faulty card as well. I would do as green suggest if you havent yet.


----------



## GetOutOfBox (Oct 17, 2008)

Yeah temps aren't a problem, since I have a huge zalman cooler, made completely from copper with a pretty high RPM fan.

I just realized that I must have edited the video BIOS before, as RBE reports that the BIOS has been edited by it. There seem to be no anomalies (it still has a PowerColor 4850 BIOS, not a 4870 transplant or whatever its called) except that the voltages were a lot higher than stock voltages (turns out 1.158 is not the default voltage for the radeon 4850 on stock clocks) so I set the voltage manually to the voltage most people said it was, 1.084.

I have yet to try overclocking again, is it possible the extra high voltage could have been messing with the overclock?

I havn't noticed any problems normally, on stock clocks it seems fine with games like Oblivion, Crysis (sometimes the 'snow' artifact appears, looks like little white specks that move around,but apparently thats a problem with the game that a lot of people have) and Furmark (stability test). Is it possible that the long period of overvoltage just handicapped the components so that they will struggle above stock voltages? and is 1.158 enough to damage it? I know the Radeon 4870 (much higher memory clock, since it has GDDR5 vs the 4850's GDDR3) has a voltage of 1.26.


----------



## greenbrucelee (Apr 24, 2007)

your board is pushing the fsb for the card when you push up the clock set the pcie frequency in the bios to 100 to make sure it doesn't


----------



## GetOutOfBox (Oct 17, 2008)

Could my problems be caused by the PSU? I bought it a while ago, I remember just looking for a PSU that had fail-safe circuits (so that if it died, it wouldn't bring the rest of the components with it), I didn't buy a really good one. Could this problem be caused by it not being able to provide enough amperage or something? I believe its a 550W PSU, is that enough for the following components:

Phenom 2 X3 (4th core unlocked and stable) 2.5GHZ model 705e (Heka)
3GB DDR2 RAM, CAS 5, 333 mhz
1GB Radeon 4850
1 DVD-RW
Creative X-Fi Titanium PCIe (1x)
ATX Motherboard
1 32GB SATA2 SSD (MLC)
1 SATA2 HDD 200GB, 7200 RPM

I know its at least pushing the limit, but everything currently seems stable. I don't exactly have a lot of cash lying around, but should getting a new (and good bran, i.e Corsair or OCZ) PSU be a priority? If so, any reccomendation for a good PSU under $150? I'm not planning on ever having a hardcore, 3 card crossfire system or something, just a mid-range gaming system. I'd like some overclocking room though.


----------



## MonsterMiata (Jan 5, 2010)

Whats the brand of the 550w unit?


----------



## GetOutOfBox (Oct 17, 2008)

Don't know, Stickers gone and newegg for some reason cleared my order history.

I can guarantee you it wasn't a good brand, I was really short on cash when I bough the parts for this computer, and yes I broke the rule of never skimping on power supplies.


----------



## GetOutOfBox (Oct 17, 2008)

http://www.newegg.ca/Product/Product.aspx?Item=N82E16817339012

That's my PSU, and yes I am ashamed.


----------



## MonsterMiata (Jan 5, 2010)

Its a good possibility than if there isn't sufficient amperage on the 12v


----------



## GetOutOfBox (Oct 17, 2008)

MonsterMiata said:


> Its a good possibility than if there isn't sufficient amperage on the 12v


So maybe there's just barely enough to keep it going at stock speeds.

Is there any other reason a card wouldn't overclock, but have no trouble at stock? I can't think of how a card could be broken 'perfectly' so that it works fine at default settings, but once you overclock it craps out. I just want to be sure its worth getting a new PSU.


----------



## GetOutOfBox (Oct 17, 2008)

I just used this calculator to calculate required wattage and amps (focusing on the 12 volt rails) http://www.extreme.outervision.com/PSUEngine

Turns out I need 35.1 AMPs for my setup (thats with stock settings), and my PSU can only provide 31. So if overclocking puts more stress on the 12Volt rail, then that gap will just get bigger.

I guess a new PSU is definetly in order then. New 24" monitor, you'll have to wait a little while.


----------



## GetOutOfBox (Oct 17, 2008)

This is the PSU I'm looking at, is it a good choice? Has a nice 150W breathing room for my components, since I only need 600W, and a 60Amp single 12-volt rail, 2 140MM fans, 80 Plus Certified.

http://www.newegg.ca/Product/Product.aspx?Item=N82E16817139006


----------



## GetOutOfBox (Oct 17, 2008)

Ok, I just switched my GPU to the first PCIe 16x slot, and it still only runs at 8x. I've read the performance difference is very minimal, but it worries me that this alongside the OC issue indicates some bigger problem.

I tried running Furmark in windowed mode then opening GPU-Z (maybe it downscales when idle), but it still runs at 8x when stressed. My motherboard isn't low-end either, its a MSI 790XT-G45.


----------



## MonsterMiata (Jan 5, 2010)

Well even though your PSU says it puts out 31A thats under ideal conditions. With Efficiency ratings taken into account its much lower. That PSU is a great choice and it is starting to sound like the card is faulty because it should still utilize all 16 lanes.


----------



## GetOutOfBox (Oct 17, 2008)

I'm buying a 4870. Hopefully that will fix the problem.


----------

