4870 Overclocking Thread

[SNiiPE_DoGG]

My HIS 4870 1 GB sucks : it is cooled by a phase change cooler, at -38°C (core temperature) and in 3DMArk06, it is stable at 951 Mhz max (1010 Mhz for the RAM). And the games are stable from 895 (Condemned) to 970 Mhz (hellgate). Most of them are stable at 920 Mhz. Pretty bad since I expected a 40 % overclock like my previous 9800 GTX. Here, I obtain around a 20 % overclock. Since the memory IO is far hotter than the core (between 10°C and 15°C more), checked with Riva Tuner 2.11, I assume that the memory controller is limiting my overclock ability. Since it is a 1 GB card, the memory controller might be stressed more than with 512 MB ?

I will sell it and buy a 4870X2 instead. I don't want to buy a second 4870 1 GB and obtain such a crappy overclock again.

Well you can't compare percentage overclocks 1:1, Nvidia architecture tends to scale to higher frequencies with less gain. I think if you did a performance scale comparison you would find that the cards overclock about the same. Its a shame you cant reach for 1ghz @ benches. I think the Issue is OVP @ 1.5v on these cards although we don't want to start killing them.

[overclock]

Well you can't compare percentage overclocks 1:1, Nvidia architecture tends to scale to higher frequencies with less gain. I think if you did a performance scale comparison you would find that the cards overclock about the same. Its a shame you cant reach for 1ghz @ benches. I think the Issue is OVP @ 1.5v on these cards although we don't want to start killing them.

With a 2900 Pro 1 GB, watercooled by a waterchiller (water temperature = 15°C), I had reached 900 Mhz at 1.15 V and 990 Mhz at 1.35 V.

Here, I reached 900 Mhz under phase : even compared to the 2900 Pro card, it is disappointing. And 2900 cards are famous for heating much.

[twwen2]

I've had my geCube 4870 512MB for a few months now, and just installed it in a new vista system.

I had been running the Asus top bios (gpu=815 mem=925) which got me around 14.5k in 3dMark06, default settings.

Today i used RBE1.13 to mod the bios, and flashed it succesfully to gpu=850, mem=1000. The flash worked, and after a reboot GPU-Z reported everything correctly, along with the increased bandwidth (128GB/s).

However, i ran 3dMark06 again, and now the score has dropped to 11k.
Nothing else was changed, the tests were run back-to-back (before and after flashing).

CPU is E8600@4GHz, the rest in my sig.

Anyone got any ideas as to why my score dropped so much???

[alexio]

I've had my geCube 4870 512MB for a few months now, and just installed it in a new vista system.

I had been running the Asus top bios (gpu=815 mem=925) which got me around 14.5k in 3dMark06, default settings.

Today i used RBE1.13 to mod the bios, and flashed it succesfully to gpu=850, mem=1000. The flash worked, and after a reboot GPU-Z reported everything correctly, along with the increased bandwidth (128GB/s).

However, i ran 3dMark06 again, and now the score has dropped to 11k.
Nothing else was changed, the tests were run back-to-back (before and after flashing).

CPU is E8600@4GHz, the rest in my sig.

Anyone got any ideas as to why my score dropped so much???

You could decrease the vRAM clock and if that doesn't work decrease the GPU clock. GDDR5 has a very strong mechanism for correcting errors so it can clock very high but clocked too high it will be slower because packages have to be re-requested () and resend.

[twwen2]

You could decrease the vRAM clock and if that doesn't work decrease the GPU clock. GDDR5 has a very strong mechanism for correcting errors so it can clock very high but clocked too high it will be slower because packages have to be re-requested () and resend.

Right!
I just learnt something, thanks!

I couldn't comprehend how an increase in clocks could possibly lead to less performance, but that makes total sense.

It is slightly dissapointing, seeing as the ram is rated at 1000MHz.

[twwen2]

Hmm, well i downclocked to 850/950, and the score dropped another ~150 points. Then i tried 820/950, still the same. These were all modified versions of the Asus "Top" bios, using RBE1.13.

After flashing back to the origional asus top bios (815/925), my score has jumped up to 15,171! That's even higher than before!!!!??? There was nocitably more FPS in every test (i'm talking an extra 25-30fps), even the two CPU tests were faster.

I'm at a loss!
Downclocking FTW!?

[alexio]

Hmm, well i downclocked to 850/950, and the score dropped another ~150 points. Then i tried 820/950, still the same. These were all modified versions of the Asus "Top" bios, using RBE1.13.

After flashing back to the origional asus top bios (815/925), my score has jumped up to 15,171! That's even higher than before!!!!??? There was nocitably more FPS in every test (i'm talking an extra 25-30fps), even the two CPU tests were faster.

I'm at a loss!
Downclocking FTW!?

What happens when you overclock with the standard BIOS? It could be that the performance profiles were messed-up in the TOP BIOS or that the driver had problems with that BIOS somehow. Just remember that it's not a good idea to use a BIOS with different vRAM frequencies in different profiles. You'll get a weird switching effect when running 3D benches.