Quantcast Laptop Forums and Notebook Computer Discussion - View Single Post - S-XPS 1645 AC Power Throttle Issue Investigation
View Single Post
Old 12-10-2009, 05:57 PM   #1009 (permalink)
theoak
Notebook Consultant
 
Join Date: Oct 2006
Posts: 296
Rep Power: 15 theoak will become famous soon enough
Default Re: S-XPS 1645 AC Power Throttle Issue Investigation

Quote:
Originally Posted by PsYcNeT View Post
So I'm trying out a few things while bored at work today with the brightness part of the problem. You guys all like Prime95 and Intel Burn Test, but I'm more partial to Cinebench 10 64-bit mulitcore test for pure CPU pushing.

Cinebench10 64 makes all C0 states stay at 100 for the test duration, so I decided to try it in conjunction with Furmark for some AC tests.

Setup: 720qm, WLED, 90w IN, restart after every test, battery NOT fully charged.

The 1645 has 15 levels of brightness, which work out to about 7% per, give or take.

Test 1: CB10 alone
All brightness levels have no effect, multiplier runs solid ~12.1x for entire test, with all C0 levels at 99.9-100.

Test 2: CB10 w/ Furmark @ 800x600 (window)
I start Furmark with the render toggled 'off' (spacebar) which means the GPU is doing no work. ~12.1x multi and ~100 C0. When Furmark is toggled 'on', the multiplier immediately drops to 7.0, and the C0 level is halved. This is at '0%' brightness.

Test 3: Furmark alone, 800x600 window, incrementally increasing brightness every 20 seconds
Every time there is a brightness increase, the multiplier dips to 8.0-10.0x, but soon rises back to 9.5-12x about 1-2 seconds later. Once you pass brightness level 12, it begins to dip to 7.0x before rising back up, but starts to fluctuate between 7.0-9.0x. At level 14 (1 below max), it locks down to 7.0x, never to rise again. C0 levels averaged ~14-15% the entire test.

Test 4: Furmark alone, 1024x768 window, incremental brightness increase again
More or less the same deal as above, except this time it bombed down to the 7.0-9.0x multiplier at level 9, and settled on level 13 at 7.0x. Interestingly, at levels 11/12, it would drop to 7.0x and hang, but rise to 8.0x at times. The C0 level was anywhere from 11-20%.

Test 5: Furmark alone, fullscreen 1600x900, incremental
Level 0 runs at 10-11x (no higher). Level 4 shows 8-11x. Hits 7.0-9.0x at level 7. Basements (hits 7.0x permenantly) at level 12.

In summation (TLDR): The less intensive the GPU use, the higher the brightness can be before the CPU basements. Fullscreen gaming is best done at levels 0 through 3, but doesn't stutter and drag-lag till ~12. I assume the numbers are probably even lower in more intensive games.
What version of the BIOS do you have?
__________________
Dell Inspiron E1705|T7200 @ 2GHz|2GB 667 MHz|UltraSharp WUXGA Display TrueLife|256MB NVIDIA 7900 GS
Dell Studio 15|Ruby Red|I5 520|1080P|ATI 5470|4GB RAM|Win7 Pro 64|320GB HD|BluRay R/W|Intel 6200 N|365 Bluetooth|9 Cell Battery|Back-lit KB
theoak is offline