#1 Edited by StrikerTheLizard (326 posts) -

Hey guys, as you can imagine, I am one of those guys who really wants to "get" how overclocking works, but completely fails at it.

To make a long story short, I bought a Geforce 640 and right now I'm trying to overclock it, but I am scared shitless by voltage clocks and memory clocks and so on.

I'm using MSI Afterburner, but actually, I have no idea what I'm doing. Any help? Pointers? I also know about FurMark.

#2 Posted by JJWeatherman (14795 posts) -

I don't know a ton about it myself, but I plan to dive into it the next time I build a PC.

From what I've seen, graphics card stuff seems fairly simple with the help of some software such as Afterburner. Generally there are just sliders for core clock and memory clock. I've messed around in Catalyst Control Center, but my games usually crash fairly quickly when I try to overclock, so I leave it alone. Either my motherboard doesn't like it, the GPU itself doesn't like it, or a combination of the two.

#3 Posted by Anobix (43 posts) -

For graphics card overclocking you just need to watch your temperatures. Because of how the 6** series cards from nVidia overclock there isn't too much you can really do to hurt them as they boost and drop speeds depending on the temperatures. I believe they 'throttle' (or at least no longer 'boost') at about 75C. I would use Afterburner to run some stress tests, I don't recommend FurMark as it creates a very unnatural amount of heat, I would use either the newest 3DMark or Unigene Heaven or Valley with a couple of loops to see how it performs and heats up. You may also need to play with your fan profile settings to keep the temperatures in check.

#4 Edited by Devildoll (943 posts) -

there's nothing called a voltage clock, not regarding regular overclocking anyway.

what you want to do is gradually bump up your core clock and then stresstest, repeat, until you start getting artifacts ( graphical errors ).
then you now you know your core clocks max, at this this present voltage, and with these fan settings.

Since you have an Nvidia card, you would probably gain something from increasing the shader clock.
Be sure to crank the core clock back to stock first, so that it does not interfere with you finding you shader max.

depending on your card, and how much you benefit from memory overclocking, you now do the same with the memory clock.
Again, don't forget to run everything else on the card at stock when you are testing the waters.

Now you know all your maxes, time to try em all together, usually you have to settle for a tad bit under, since running em all overclocked at once produces additional stress.
If you are a beginner, this is where you stop.

then if you want to get into increasing voltages, you simply notch up the voltage, and test how much further you can push the clocks, via the above described methodology. repeat until you hit too high temperatures, or you are hitting the voltage ceiling or what is considered a safe voltage by the community/manufacturer.

For stresstests, you can run something like furmark, i personally haven't used it in a long while, i simply run a demanding game instead.

#5 Edited by Subject2Change (2971 posts) -

Overclocking your Graphics card is silly for the potential damage vs performance gain, especially on a budget card like a GT640. I use my GT640 to run my 2nd and 3rd monitor...

#6 Edited by WasabiCurry (430 posts) -

As a regular Overclocking user there are few pointers I could share.

1. Steady as she goes. Whenever you start Overclocking a Graphics, you tend to want to increase only in small intervals. I have seen many people who are new in OC tend to put everything at max and wonder why they BSOD so fast when they play a game. A good number is to increase between 5-15 MHz for the memory and core clock speeds. You want to feel the card out. Thus testing it with high demanding games will be frequent.

2. Mileage may vary. When I say this, I mean that it really depends on the game. Do you really need to OC a pixel game such as Terraria or Shank 2? No. It will just do fine under normal loads. Typically, you want to OC on games such as Borderlands 2, Chivalry, and fps games such as Black Light Retribution.

3. Keep your expectations reasonable. You may see a huge performance gain (5-15 Frames Per Second at the same settings) in certain games while others barely improve. It is just the nature of the beast since no Graphic Card can output the same as another.

4. Let's talk about Voltage. Here is where misconception comes into play. You will not kill your GPU by bumping up your Core Clock or Memory Speed, if the card cannot handle it. It will simply BSOD before any real damage can be done. Voltage is an entire different animal. Basically, you up the wattage of your GPU and in return for the significant increase in heat, you are able to increase the Core Clock Speed and Memory Speed. Let us say you got a stable OC at stock voltage which would .5v at 950 MHz and 1300 MHz for the memory. However, you know the GPU would be unstable at 1030 MHz and 1450 MHz at .5v voltage. So you increase the voltage to 1.0v and you are now able to stay stable at 1030 MHz and 1450 MHz. It is dangerous and the numbers are only imaginary. That is why it is recommended not to mess around the voltage unless you are certain you have the knowledge to OC voltage. ELECTRICITY!

5. Look up guides and OC benchmarks for your GPU. There are some insane GPU benchmarks out there. Trust me, I saw that a guy actually got my laptop for run at 185 MHz on the CPU and stable at that! You could be one of the lucky or unlucky ones that see these gains.

6. Set Fan Speed to Stun! As you begin OC, you may notice that your GPU is running a little hotter. Begin worried, you may want to increase the fan speed; however, you do not want to damage your fan. It is a stock fan after all. Here is why it depends on the manufacturer. Take an example from Asus. Their GPU fans are meant to take the increase in speed, however, a stock Nvidia card cannot! If you wish to increase your fan speed, take it slow. Increase the RPM very slowly. About 50 - 100 RPM increase.

If you need anymore questions, I will be happy to answer.

#7 Posted by gaminghooligan (1670 posts) -

@wasabicurry: As someone who came in this thread looking for advice, this post was great, thank you!

#8 Posted by StrikerTheLizard (326 posts) -

@WasabiCurry: Thanks for the awesome advice. The only thing I don't quite get is the fan speed. MSI Afterburner also has an AUTO setting for the fan and I'm wondering if that's enough or should I crank it up just a little bit just to be sure?

Also, a big thank you to everyone else who gave advice!

#9 Edited by Devildoll (943 posts) -


ive overclocked every card i have owned, none have broken.

as long as you know the limits, its not going to break much faster than running it stock, cause, there's no such thing as "stock"

The manufacturer has a chip, they test the chip and see how far they can bump up the clocks while still keeping it stable, decide upon a frequency to ship the card with, and do so.

There is no frequency sanctioned by god as the point where a card will start to break.

Voltage on the other hand, can do some real damage.
Most overclocking suites like MSI Afterburner and such don't have sliders that go far enough for a user to instantly fry a card however.

As long as you've researched the limits and keep an eye on the temps, you're golden.

But yeah, regarding the 640, an overclock will allow you to run a modern game at unplayable, instead of unplayable.....

Might come in handy for older titles though.

#10 Edited by WasabiCurry (430 posts) -

@strikerthelizard: I won't use MSI Fan Control because it doesn't tell what the is RPM of your fans. I use this nifty little program to increase my fan speed. I must say beforehand that you should use caution when using this program. It will definitely tell you the RPM of your fans and allow you to adjust every set value. However, it can cause damage to your card if you set them too high.

The program can be a little less intuitive than MSI so if you need help in understanding values. I can upload some pictures for you.

@gaminghooligan Your welcome, I try to help when I can.