Spirou
New Member
- Joined
- Apr 7, 2008
- Messages
- 73 (0.01/day)
- Location
- Erkelenz, Germany
System Name | Sophost |
---|---|
Processor | Intel Q6600 @ 3520 MHz |
Motherboard | Asus Maximus Formula |
Cooling | Thermalright IFX-14 & Scythe Kama PWM |
Memory | Kingston 2*1GB PC2-5300 @ 440 MHz (4,4,4,12) |
Video Card(s) | Sapphire Silent HD3870 (11122-05) @ 931/1332 |
Storage | Samsung HD501LJ & SP2504C |
Display(s) | LG L1970H & Sampo Alphascan 871 |
Case | Thermaltake Soprano |
Audio Device(s) | SupremeFX II |
Power Supply | LC Power Super Silent Black LC6550 |
Software | XP Pro, Apache PHP & MySQL, WinMX |
Benchmark Scores | 3dMark06: 14386, Fur: 3870, ATT: 19290.9 |
Yes, i strongly believe it does. Some say it doesn't.
In theory there must be some dependancy between GPU speed and memory speed, and setting up different clock speeds should show which of both is the limiting factor.
Taking in account that it's difficult to determine how different clock settings influence game performance due to the sheer amount of cross dependencies, i simply tested different clock settings using Ati Tray Tools' internal benching facility with my Sapphire HD 3870 Dual Slot.
Common clock-settings sorted by result:
GPU/Mem (MHz) Result, Comment
-----------------------------------------------
904.50/0999 = 14219,20 very high GPU, low mem
776.25/1125 = 15891,41 reference GPU, ref mem
904.50/1125 = 16063,80 very high GPU, ref mem
796.50/1152 = 16274,39 S.Toxic GPU & mem
796.50/1197 = 16773,16 typical OC GPU & mem
823.50/1197 = 16910,54 typical OC GPU & mem
850.50/1197 = 17018,82 S.Atomic GPU & mem
695.25/1341 = 17370,40 low GPU, extreme mem
850.50/1251 = 17661,97 high GPU, high mem
904.50/1251 = 17887,53 very high GPU, high mem
776.25/1341 = 18068,95 reference GPU, extreme mem
850.50/1296 = 18105,02 Atomic GPU, very high mem
904.50/1296 = 18488,85 very high GPU, very high mem
904.50/1305 = 18560,28 very high GPU + 0.0, mem + 9
904.50/1323 = 18758,06 very high GPU + 0.0, mem + 27
918.00/1323 = 18851,14 very high GPU + 13.5, mem + 27
918.00/1332 = 18921,22 very high GPU + 13.5, mem + 36
931.50/1332 = 19003,25 very high GPU + 27.0, mem + 36
945.00/1332 = 19077,39 very high GPU + 40.5, mem + 36
931.50/1341 = 19107,60 very high GPU + 27.0, mem + 45
945.00/1341 = 19188,50 very high GPU + 40.5, mem + 45
945.00/1350 = 19290.98 very high GPU + 40.5, mem + 54
958.50/1350 = unstable very high GPU + 54.0, mem + 54
Highest stable test so far:
I also tested some extreme combinations to find an optimum ratio between GPU and memory clocks which can be described as a sweet spot. It's also clear to see, where limitation steps in. Optimum ratio seems to be between 9/13 (reference clock ratio) and 2/3 on first sight, but even at 776 MHz GPU an extreme memory overclock shows how important bandwidth is for the HD 3800 Series.
Hope this tests can help to decide which overclock should work best, or wether or not a given model can be expected to be a good choice. My advice: stay away from GDDR3 or models labeled as turbo or oc, which IMHO are not as fast as you would expect.
Depending on heatsink (mine did all this tests at 45 degrees) and different voltage regulators all HD 3870 should reach nearly 900 MHz and due to the specs of GDDR4 all should reach 1250 MHz without voltmodding.
Another session using FurMark v1.3, results by GPU clock:
GPU/Mem (MHz) Result, Comment
-----------------------------------------------
695.25/1341 = 2850 low GPU, extreme mem
776.25/1125 = 3181 reference GPU, ref mem
776.25/1341 = 3181 reference GPU, extreme mem
796.50/1152 = 3263 Toxic GPU & mem
796.50/1197 = 3262 typical OC GPU & mem
823.50/1197 = 3371 typical OC GPU & mem
850.50/1197 = 3479 Atomic GPU & mem
850.50/1251 = 3483 high GPU, high mem
850.50/1296 = 3483 Atomic GPU, very high mem
904.50/0999 = 3660 very high GPU, low mem
904.50/1125 = 3695 very high GPU, ref mem
904.50/1251 = 3702 very high GPU, high mem
904.50/1296 = 3701 very high GPU, very high mem
904.50/1305 = 3703 very high GPU + 0.0, mem + 9
904.50/1323 = 3703 very high GPU + 0.0, mem + 27
918.00/1323 = 3755 very high GPU + 13.5, mem + 27
918.00/1332 = 3758 very high GPU + 13.5, mem + 36
931.50/1332 = 3815 very high GPU + 27.0, mem + 36
931.50/1341 = 3812 very high GPU + 27.0, mem + 45
945.00/1332 = 3868 very high GPU + 40.5, mem + 36
945.00/1341 = 3867 very high GPU + 40.5, mem + 45
945.00/1350 = 3866 very high GPU + 40.5, mem + 54
958.50/1350 = ---- very high GPU + 54.0, mem + 54
As you see, there is no difference between various mem clocks. All results depend on GPU clock only. FurBench seems to use data from internal buffers in GPU, which is not accurate, because gaming performance is always a mix of calculation and data throughput.
Assumingly there'd be no difference in FurMark results for 3870 and 3850 set to same GPU clocks.
I will add another series using Canyon Flight soon. Anyone with a HD 3850 who could confirm some of the tests?
Comment if you like, or add different clock speeds if you wish. I will add them to this list.
In theory there must be some dependancy between GPU speed and memory speed, and setting up different clock speeds should show which of both is the limiting factor.
Taking in account that it's difficult to determine how different clock settings influence game performance due to the sheer amount of cross dependencies, i simply tested different clock settings using Ati Tray Tools' internal benching facility with my Sapphire HD 3870 Dual Slot.
Common clock-settings sorted by result:
GPU/Mem (MHz) Result, Comment
-----------------------------------------------
904.50/0999 = 14219,20 very high GPU, low mem
776.25/1125 = 15891,41 reference GPU, ref mem
904.50/1125 = 16063,80 very high GPU, ref mem
796.50/1152 = 16274,39 S.Toxic GPU & mem
796.50/1197 = 16773,16 typical OC GPU & mem
823.50/1197 = 16910,54 typical OC GPU & mem
850.50/1197 = 17018,82 S.Atomic GPU & mem
695.25/1341 = 17370,40 low GPU, extreme mem
850.50/1251 = 17661,97 high GPU, high mem
904.50/1251 = 17887,53 very high GPU, high mem
776.25/1341 = 18068,95 reference GPU, extreme mem
850.50/1296 = 18105,02 Atomic GPU, very high mem
904.50/1296 = 18488,85 very high GPU, very high mem
904.50/1305 = 18560,28 very high GPU + 0.0, mem + 9
904.50/1323 = 18758,06 very high GPU + 0.0, mem + 27
918.00/1323 = 18851,14 very high GPU + 13.5, mem + 27
918.00/1332 = 18921,22 very high GPU + 13.5, mem + 36
931.50/1332 = 19003,25 very high GPU + 27.0, mem + 36
945.00/1332 = 19077,39 very high GPU + 40.5, mem + 36
931.50/1341 = 19107,60 very high GPU + 27.0, mem + 45
945.00/1341 = 19188,50 very high GPU + 40.5, mem + 45
945.00/1350 = 19290.98 very high GPU + 40.5, mem + 54
958.50/1350 = unstable very high GPU + 54.0, mem + 54
Highest stable test so far:
I also tested some extreme combinations to find an optimum ratio between GPU and memory clocks which can be described as a sweet spot. It's also clear to see, where limitation steps in. Optimum ratio seems to be between 9/13 (reference clock ratio) and 2/3 on first sight, but even at 776 MHz GPU an extreme memory overclock shows how important bandwidth is for the HD 3800 Series.
Hope this tests can help to decide which overclock should work best, or wether or not a given model can be expected to be a good choice. My advice: stay away from GDDR3 or models labeled as turbo or oc, which IMHO are not as fast as you would expect.
Depending on heatsink (mine did all this tests at 45 degrees) and different voltage regulators all HD 3870 should reach nearly 900 MHz and due to the specs of GDDR4 all should reach 1250 MHz without voltmodding.
Another session using FurMark v1.3, results by GPU clock:
GPU/Mem (MHz) Result, Comment
-----------------------------------------------
695.25/1341 = 2850 low GPU, extreme mem
776.25/1125 = 3181 reference GPU, ref mem
776.25/1341 = 3181 reference GPU, extreme mem
796.50/1152 = 3263 Toxic GPU & mem
796.50/1197 = 3262 typical OC GPU & mem
823.50/1197 = 3371 typical OC GPU & mem
850.50/1197 = 3479 Atomic GPU & mem
850.50/1251 = 3483 high GPU, high mem
850.50/1296 = 3483 Atomic GPU, very high mem
904.50/0999 = 3660 very high GPU, low mem
904.50/1125 = 3695 very high GPU, ref mem
904.50/1251 = 3702 very high GPU, high mem
904.50/1296 = 3701 very high GPU, very high mem
904.50/1305 = 3703 very high GPU + 0.0, mem + 9
904.50/1323 = 3703 very high GPU + 0.0, mem + 27
918.00/1323 = 3755 very high GPU + 13.5, mem + 27
918.00/1332 = 3758 very high GPU + 13.5, mem + 36
931.50/1332 = 3815 very high GPU + 27.0, mem + 36
931.50/1341 = 3812 very high GPU + 27.0, mem + 45
945.00/1332 = 3868 very high GPU + 40.5, mem + 36
945.00/1341 = 3867 very high GPU + 40.5, mem + 45
945.00/1350 = 3866 very high GPU + 40.5, mem + 54
958.50/1350 = ---- very high GPU + 54.0, mem + 54
As you see, there is no difference between various mem clocks. All results depend on GPU clock only. FurBench seems to use data from internal buffers in GPU, which is not accurate, because gaming performance is always a mix of calculation and data throughput.
Assumingly there'd be no difference in FurMark results for 3870 and 3850 set to same GPU clocks.
I will add another series using Canyon Flight soon. Anyone with a HD 3850 who could confirm some of the tests?
Comment if you like, or add different clock speeds if you wish. I will add them to this list.
Last edited: