do some BIOS's overclock better than others?

I can't understand this.

I maxed out my Visiontek GeForce2 GTS-V 32MB DDR (175/246 stock) at 205/336 before it would lock up. Actually, it never gave me any artifacts or tearing. It ran fine until it locked up on the high quality test of The Lobby (3DMark2001SE). Weird...

But anyway, I flashed it with the OEM BIOS of a GTS card (200/333), and now I can take the settings up to 195/380 stable (205/385 will lock up, and 190/390 has sooooo many artifacts it ain't funny). I tried to duplicate these settings with the GTS-V BIOS, but it won't do it.

Can someone explain why I can o/c better with the GTS BIOS? I would have thought that the limits of a card would be the limits under all circumstances, but I can go higher with one than I can with another?

takiwa said:

I can't understand this.

I maxed out my Visiontek GeForce2 GTS-V 32MB DDR (175/246 stock) at 205/336 before it would lock up. Actually, it never gave me any artifacts or tearing. It ran fine until it locked up on the high quality test of The Lobby (3DMark2001SE). Weird...

But anyway, I flashed it with the OEM BIOS of a GTS card (200/333), and now I can take the settings up to 195/380 stable (205/385 will lock up, and 190/390 has sooooo many artifacts it ain't funny). I tried to duplicate these settings with the GTS-V BIOS, but it won't do it.

Can someone explain why I can o/c better with the GTS BIOS? I would have thought that the limits of a card would be the limits under all circumstances, but I can go higher with one than I can with another?

Click to expand...

It would more than likely have to do with changed memory timings. One bios may have the most aggressive timings where as another may have just one less aggressive setting for stability... allowing for a higher stable overclock

takiwa,

This is exactly what I did to my GF2MX BIOS ... tweak the memory settings so that I could overclock it further... max was 180Mhz and now it is 210Mhz by relaxing the ras2cmd timing, so it makes sense that manufacturers try to adjust mem timings to the best possible settings for the memory they are putting on the cards.

Regards
FTC

How much does sacraficing mem timings for more MHz affect the speed? In my BIOS I set the AGP timings to max, if I relaxed those I might get farther but would it help much?

--Illah

Illah,


Sorry, I may have confused you a bit. I was NOT talking about main memory bios timings, but the video card memory timings. These are NOT adjustable through machine's BIOS. What I did to adjust those was patch and create my own version of the video card BIOS (completely different thing from the machine BIOS), with a binary editor and test those with VGABIOS tool until I was happy. After that I reflashed my card with the help of NVFLASH.

All of this is a trial and error process, where you overclock video card memory until artifacts or unstabilities are being found. After that, you relax all video bios memory timings and see if this solves it. If it does, then again adjust timings until finding which one did solve the artifacts... and start over overclocking... until a point where you do not get added performance or unstabilities are caused by other things (not vid-card memory).
In my case, I could improve memory overclockability from 166 (card's default), 180 (max oc reachable with default video bios) to 210 Mhz. This, together with core overclock from 175 to 212, was responsible for a 3DMK2001 increase of roughly 250 points, on top of the 150 already gained by 'regular' video card overclocking', which is not bad at all for a GF2MX. Note that I had to go this route because my video card memory was such a bad overclocker with default video BIOS (only 166->180).

I don't think that main memory timings do have a noticeable effect on video card overclockability. AGP settings may have a bit more effect, in terms of core heat generation, but nothing else.

Hope this helps a bit.
Regards
FTC

Yeah, I understood that you were talking about the video bios, but in my regular bios I have the options of more agressive AGP timings, either 1T or 2T. I'm not sure how much it really afects the card though.

--Illah