Another stubborn X4 945 (125W) C2 Overclocker

Greetings all! In 2009 I built this gaming rig to be a little "future proof" but as we all know that is impossible to actually accomplish with the rate at which things change! Anyway, here is my rig:


Case: Zalman GS-1000-BK
Newegg.com - ZALMAN PROFESSIONAL GS-1000-BK Black Computer Case Aluminum / 1.0mm SECC Steel Full Tower With Hot Swap Bays & PSU Roller Rails

MoBo: Gigabyte MA790FXT-UD5P (AM3, DDR3 capable)
Newegg.com - GIGABYTE GA-MA790FXT-UD5P AM3 DDR3 AMD 790FX ATX AMD Motherboard

CPU: AMD Phenom II X4 945 Deneb 3.0GHz (125W) C2 Stepping
Newegg.com - AMD Phenom II X4 945 Deneb 3.0GHz Socket AM3 125W Quad-Core Processor HDX945FBGIBOX

CPU Cooler: Swiftech H20-220 Edge HD (Appogee Waterblock) Water cooling kit using the Swiftech Thermal Paste

RAM: 4x2GB G.SKill DDR3 1333 (PC3 10666)
Newegg.com - G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Dual Channel Kit Desktop Memory Model F3-10666CL8D-4GBHK

HD: 1TB Western Digital WD (7200 RPM SATA 3.0GB/s)
Newegg.com - Western Digital WD Black WD10000LSRTL 1TB 7200 RPM SATA 3.0Gb/s 3.5" Hard Drive

Video Card: Sapphire Vapor-X Radeon HD4870 2GB (GDDR5)
Newegg.com - SAPPHIRE Vapor-X Radeon HD 4870 2GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFireX Support Video Card

PSU: 1000W continuous Zalman ZM1000-HP PSU (overkill, I know, too late!)
Newegg.com - ZALMAN ZM1000-HP 1000W Continuous @ 45°C
(Maximum Continuous Peak: 1250W) ATX12V V2.2 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS Certified Modular Active PFC Modular Heatpipe-Cooled SLI Power Supply

The case has been modified a little bit as we all know that these GS1000's tend to have really bad cooling:




The fan guards are just on the fans right now, the black cover hasn't been put on yet because I haven't cut the holes for the fans yet, this was just a mock up photo. The fans on top are free flowing!


And of course with everything all assembled:


Fans, lets see, the 2 stock Zalman 120mm Quiet Fans, one is at the top rear exhaust port (exhausting, obviously) and the other is free standing in the case blowing over the GPU. I have the two Swiftech 120mm fans blowing down through the radiator at the top and a Swiftech 140mm on the bottom blowing in.

Alright, stop jaw flapping Whiskey! On with the good stuff! So my goal for this rig was to get over 3.75GHz (hence the water cooling). I believe these are the 3 pages from CPU-Z and HWM that you will most likely ask for?:


My OCing experience is pretty minimal. This is my first OC that requires voltage changes and to be honest, even after following several of the guides here, I still can't quite get as high as I want. I understand that the 125W C2 945's are kind of limited in max clocks but I'm hoping that with all of your help that I can get a little higher! I'm sure the CPU Voltage is on the high side. I went up 2 notches in the BIOS and then said "ahh screw it!" and threw it to 1.5v in the BIOS. It could probably come down some and still be stable. Something to try when I have more time! I literally just got the Swiftech installed today and before was running an OOOOOLLLLLLLLDDDDDDDDD Zalman 9500 air cooler that wouldn't allow me much more than 3.45GHz before Core Temps would jump to over 55ºC and would crash in Prime95. I did a quick run of Prime 95 Blend on this 3.6GHz clock and it ran for 20 minutes without issue.

Anyway, let me know if there is anything else you need me to post!

Unfortunately, your CPU is the C2 stepping and I'm guessing you have hit the wall at 3.6. The fact that with the old air cooler installed it was unstable when the core temp hit 55c is pretty indicative that your processor has a pretty definite heat wall at the classic 55c point we always preach about. You will need to run the Prime95 blend test for at least 2 hrs. to confirm stability. The other thoughts I have is that running four sticks of ram may be holding you back a little due to placing extra load on the integrated memory controller, especially in that your timings look a little aggressive to me. Compare your current memory timings in the CPU-z memory tabe vs. what you see the manufacturer recommending in the SPD tab JEDEC columns. Your current timings are appropriate for JEDEC #3 while your current frequency more closely matches JEDEC #4. You might try relaxing them a bit.

trents said:

Unfortunately, your CPU is the C2 stepping and I'm guessing you have hit the wall at 3.6. The fact that with the old air cooler installed it was unstable when the core temp hit 55c is pretty indicative that your processor has a pretty definite heat wall at the classic 55c point we always preach about. You will need to run the Prime95 blend test for at least 2 hrs. to confirm stability. The other thoughts I have is that running four sticks of ram may be holding you back a little due to placing extra load on the integrated memory controller, especially in that your timings look a little aggressive to me. Compare your current memory timings in the CPU-z memory tabe vs. what you see the manufacturer recommending in the SPD tab JEDEC columns. Your current timings are appropriate for JEDEC #3 while your current frequency more closely matches JEDEC #4. You might try relaxing them a bit.

Click to expand...

Thanks for the response trents! I let Prime95 run last night and it ran for a total of 6 hours without failure or error on all 4 workers. I shut it off when I woke up this morning when it reached 6 hours so it looks like the 3.6GHz is stable. Max temp recorded in HWM was 55ºC for the cores (I forgot to look at the TMPIN01 for actual CPU temp) but the immediate temperature was 53ºC for the cores and it looked like it was falling. I haven't tried bumping the FSB any further to see if it will be stable any faster. I did try 250 FSB last night just for grins and it gave me the "Boot failed due to overclocking" message at post and that is when I tried to go up to 240 FSB for 3.6GHz and decided to let Prime95 Blend run last night.

The memory timings for this RAM is 8-8-8-21 from the factory at 1.5V (notice that my MoBo defaults to 1.6V and wont let me downrate the voltage any ) but I think that is at 1066 for speed. I get the same "Boot failed due to overclocking" message at Post if I relax the timings to 9-9-9-24 so maybe there is something else wrong with the RAM timings I am choosing? If I set it to "auto" it defaults to 8-8-8-20 at anything below 1333 for RAM speed and I get the "Boot failed" message again but it boots if I manually set it to 8-8-8-21? I will admit, that short of keeping the RAM frequency below the 1333 max speed for this RAM, RAM timings are a bit of a mystery. I know that lower is better but beyond that I wouldn't know the first thing beyond the basic timings.

It sounds to me like I need to give up on this 945 and maybe pick up a 965 BE if I want to go any higher? I don't necessarily have a lot of money to spend on another processor but I believe 965's can be had pretty inexpensively now.

I'm currently at work so I can't grab screenshots or try anything until way later tonight (about 11.5 hours from now) but I'll do my best to answer any other questions that I can from memory! I do need to play around with it a little still and see if I can't get it any higher. I didn't have much time last night to play around with it since setting up the watercooling loop took up a decent amount of time.

Thanks again for the response trents!

Whiskey11 said:

Thanks for the response trents! I let Prime95 run last night and it ran for a total of 6 hours without failure or error on all 4 workers. I shut it off when I woke up this morning when it reached 6 hours so it looks like the 3.6GHz is stable. Max temp recorded in HWM was 55ºC for the cores (I forgot to look at the TMPIN01 for actual CPU temp) but the immediate temperature was 53ºC for the cores and it looked like it was falling. I haven't tried bumping the FSB any further to see if it will be stable any faster. I did try 250 FSB last night just for grins and it gave me the "Boot failed due to overclocking" message at post and that is when I tried to go up to 240 FSB for 3.6GHz and decided to let Prime95 Blend run last night.

The memory timings for this RAM is 8-8-8-21 from the factory at 1.5V (notice that my MoBo defaults to 1.6V and wont let me downrate the voltage any ) but I think that is at 1066 for speed. I get the same "Boot failed due to overclocking" message at Post if I relax the timings to 9-9-9-24 so maybe there is something else wrong with the RAM timings I am choosing? If I set it to "auto" it defaults to 8-8-8-20 at anything below 1333 for RAM speed and I get the "Boot failed" message again but it boots if I manually set it to 8-8-8-21? I will admit, that short of keeping the RAM frequency below the 1333 max speed for this RAM, RAM timings are a bit of a mystery. I know that lower is better but beyond that I wouldn't know the first thing beyond the basic timings.

It sounds to me like I need to give up on this 945 and maybe pick up a 965 BE if I want to go any higher? I don't necessarily have a lot of money to spend on another processor but I believe 965's can be had pretty inexpensively now.

I'm currently at work so I can't grab screenshots or try anything until way later tonight (about 11.5 hours from now) but I'll do my best to answer any other questions that I can from memory! I do need to play around with it a little still and see if I can't get it any higher. I didn't have much time last night to play around with it since setting up the watercooling loop took up a decent amount of time.

Thanks again for the response trents!

Click to expand...

Grabbing a 965 off ebay or something similar might be a good buy. The 8350 in my siggy replaced a C2 955 x4, so I fully understand your pain. I was lucky enough to get a 3.85GHz OC out of that chip, but I'm told that was pretty darn rare for that chip. If only you could find a well-priced 1100T

Anonaru said:

Grabbing a 965 off ebay or something similar might be a good buy. The 8350 in my siggy replaced a C2 955 x4, so I fully understand your pain. I was lucky enough to get a 3.85GHz OC out of that chip, but I'm told that was pretty darn rare for that chip. If only you could find a well-priced 1100T

Click to expand...

I don't think my MoBo would support an 1100T would it? It only says X4?? I may just bite the bullet and buy the 965 BE... That might be necessary considering my "addiction" to FSX and it's horrible CPU utilization! What I'd like to do is just buy a new Mobo, CPU, RAM, and GPU but that is a bit out of the price equation!

Whiskey11 said:

I don't think my MoBo would support an 1100T would it? It only says X4?? I may just bite the bullet and buy the 965 BE... That might be necessary considering my "addiction" to FSX and it's horrible CPU utilization! What I'd like to do is just buy a new Mobo, CPU, RAM, and GPU but that is a bit out of the price equation!

Click to expand...

I'm sure it has the support, it just may not be able to supply the power required.. At any rate, the 965 is a pretty solid part and does well for itself gaming. Just make sure you get a good price on one, these are old parts now

Anonaru said:

I'm sure it has the support, it just may not be able to supply the power required.. At any rate, the 965 is a pretty solid part and does well for itself gaming. Just make sure you get a good price on one, these are old parts now

Click to expand...

Ehh, well, thinking about it I don't think the 965 would be a smart upgrade considering how short it would last me. I'm not stuck on AMD despite having run mostly AMD products for the longest time. The parent's keep bugging me for a Christmas list so I'm putting together one around an i5 3750k. I priced out going to the 8350 and it was more expensive to go that route. I'm more worried about FSX not getting enough of the CPU speed it needs to run at max with the 8350, even OCed. Pretty much everywhere I've read said that it isn't the CPU for games that are poorly optimized, err, I mean, CPU bound! I still need to do more research.

Anyway, I bumped the FSB up to 245 and I'm running Prime95 right now as I type this. It hasn't BSODed yet or no errors in this 10 minute run. I'll let it run a little bit longer and see how it goes. Water temp is already up to 51ºC though and slowly climbing. I'm probably at that "wall" for this chip!

I do have a question though, right now my CPU-NB and HT Link are about 1960 MHz. I know "around" 2000 is ideal for HT-Link, but what about the CPU-NB? How high should I take it, if it all, to improve performance? Will it even improve performance any?

Thanks in advance for the help!

Whiskey11 said:

Ehh, well, thinking about it I don't think the 965 would be a smart upgrade considering how short it would last me. I'm not stuck on AMD despite having run mostly AMD products for the longest time. The parent's keep bugging me for a Christmas list so I'm putting together one around an i5 3750k. I priced out going to the 8350 and it was more expensive to go that route. I'm more worried about FSX not getting enough of the CPU speed it needs to run at max with the 8350, even OCed. Pretty much everywhere I've read said that it isn't the CPU for games that are poorly optimized, err, I mean, CPU bound! I still need to do more research.

Anyway, I bumped the FSB up to 245 and I'm running Prime95 right now as I type this. It hasn't BSODed yet or no errors in this 10 minute run. I'll let it run a little bit longer and see how it goes. Water temp is already up to 51ºC though and slowly climbing. I'm probably at that "wall" for this chip!

I do have a question though, right now my CPU-NB and HT Link are about 1960 MHz. I know "around" 2000 is ideal for HT-Link, but what about the CPU-NB? How high should I take it, if it all, to improve performance? Will it even improve performance any?

Thanks in advance for the help!

Click to expand...

2600MHz would be good on the CPU-NB.

Special7 said:

2600MHz would be good on the CPU-NB.

Click to expand...

I'm assuming that would require a good bump in CPU-NB voltage correct? Any idea about how much it would require?

Whiskey11 said:

I'm assuming that would require a good bump in CPU-NB voltage correct? Any idea about how much it would require?

Click to expand...

Yes. 1.2-1.3 volts seems to be usually adequate. Keep the HT Link frequency at the same level or slightly lower but the HT Link does not need any extra voltage.

trents said:

Yes. 1.2-1.3 volts seems to be usually adequate. Keep the HT Link frequency at the same level or slightly lower but the HT Link does not need any extra voltage.

Click to expand...

When you say keep the HT link frequency at the same level do you mean the same as the CPU-NB or at around 2000?

I managed to get the computer to boot at a CPU-NB Frequency of 2500 at 1.3V and HT Link at 2000 but when I run Prime95 Blend one of my cores comes up with a Rounding error and stops the worker. That happened in less than a minute...

FSB is at 250, CPU Multiplier is at 14.5 (3.625GHz), RAM is at 1332 frequency. If that helps. From what I've read this is most likely a voltage issue? How much higher will the NB go?

I'm going to crash for the night, maybe I can address this tomorrow when I get off work! =\ Thanks again all for any help! It's appreciated!

You want to keep the HT Link frequency at the same level or close to the frequency of the CPUNB frequency. If CPUNB frequency is 2500 then have the HT Link the same. Lower the CPUNB and the HT Link frequency to 9x and see if stability doesn't improve. The C2 stepping CPUs had weak integrated memory controllers. And yes, you might need more CPU voltage but can your temps stand it? What were your core temps running at your highest stable overclock?

trents said:

You want to keep the HT Link frequency at the same level or close to the frequency of the CPUNB frequency. If CPUNB frequency is 2500 then have the HT Link the same. Lower the CPUNB and the HT Link frequency to 9x and see if stability doesn't improve. The C2 stepping CPUs had weak integrated memory controllers. And yes, you might need more CPU voltage but can your temps stand it? What were your core temps running at your highest stable overclock?

Click to expand...

The only clock I have tested for more than an hour or so is the 3.6GHz clock and after 6 hours of prime the max recorded core temp was 55ºC but it was sitting at 52ºC-53ºC. After an hour of the 3.675 GHZ (what was 245x15) it was about the same 52ºC-53ºC.

I rebooted up at CPU-NB/HT-Link of 250x9 (2250MHz) and it has gone through 5 minutes of testing on Prime95 without any errors. I get the distinct impression that getting it higher is going to require a lot of testing back and forth through the BIOS! That is something I will have to play with tonight.

In the mean time, I'm going to let Pimre95 run at these settings while I'm at work and see if we can get a more accurate test of max Core temp at this clock. I did play some FSX on the 3.675GHz and even though it was only .075GHz more then the 3.6GHz it ran much smoother in big cities. I was flying to Chicago Midway and it stayed above 20 FPS the entire way until I dropped the HUD in the PMDG 737 NGX down for landing. That is probably the most resource intensive part of that model despite it looking better and being more detailed then my other payware aircraft. When it did drop it dropped to around 15 FPS which is still flyable. I just want MORE! I would like some overhead there as Chicago isn't nearly as resource intensive as places like LAX or Laguardia is.

Anyway, updated CPU-Z and HWM screenshot:

Have you checked to see if it's the CPU or the video card that is being maxed out?

trents said:

Have you checked to see if it's the CPU or the video card that is being maxed out?

Click to expand...

Well, not specifically no. Each increase in CPU speed has resulted in some FPS gain. FSX is extremely CPU bound by design. Something about being "designed for the future and up to 256 cores" or something stupid. The sad reality is that the game doesn't fully utilize multiple cores anyway. If I open up task manager while playing the game the first core is barely utilized, probably 10-15% tops. Core 2 is almost fully maxed out all the time, cores 3 and 4 fluctuate between 50%-80% utilization. It's just a poorly designed game. I've done numerous tweaks to the config file for the game to try and even out the CPU usage across cores and it has resulted in no gains in FPS or the FPS fluctuation. From what I'm reading, the GPU requirements are very circa 2006 when the game launched and it doesn't really utilize the GPU to it's fullest.

Tonight when I get home I'm going to try and get frame rates at JFK or LaGuardia at the 1920x1080 resolution that I have it at and get the frames again down a step at 1680x1050(?) and see if frame rates improve. Then I'll try full screen vs windowed (but occupying the full screen) and see if that improves it any. That would be the correct way to determine if it is GPU limiting correct? Right now I'm running it windowed so I can do multitasking while flying on the other screen such as finding the correct charts and all that for airports but I've got a laptop I can use for that too at added inconvenience. I am assuming however that this is an issue specifically with the CPU bound nature of the game and not my now-ancient Sapphire 4870 HD 2GB. I could also be looking for an excuse not to spend a lot more of my own money!

Sounds like you're already on top of the GPU vs. CPU being maxed out thing. What would happen if you disabled one of the cores and went with three cores since the game seems to be only using three? That way you may be able to bet a litter higher overclock. If your board has core unlocking ability there should be a bios parameter in conjunction with that which allows you to enable/disable individual cores.

trents said:

Sounds like you're already on top of the GPU vs. CPU being maxed out thing. What would happen if you disabled one of the cores and went with three cores since the game seems to be only using three? That way you may be able to bet a litter higher overclock. If your board has core unlocking ability there should be a bios parameter in conjunction with that which allows you to enable/disable individual cores.

Click to expand...

Well, none of the settings changes really made any change in FPS more than 1 or 2 on average.

I let Prime95 run all day and when I got home I was greeted by a login screen which means that Prime95 either caused a BSOD or my computer restarted itself. I'm back at my previous settings for everything. I'm guessing this little ole chip is at it's edge and wants to jump off! Bummer!

Thanks trents and everyone for your help!

Sorry to double post but I figured I would update everyone about how stupid and stubborn I am! Yesterday I backed off the CPU core voltage down to 1.475V and let it run all day at 245x15 FSB (3.675GHz). Max temp recorded 55ºC after 9 hours of run. Today I'm feeling particularly narcissistic and decided to jump the FSB back up to 250 (3.750GHz) and let her rip without adjusting voltage. Prime95 is running right now so we will see how long it will go before it either crashes or posts an error! 10 minutes gone so far, still on the 4000 Lucas-Lehmer iterations but the 800,000's are up to really stress this bugger!

Wish me luck! Maybe the problem I've been having is having too much voltage! I'm curious trents, what's the highest you've seen a C2 945 125W go with "conventional" cooling (air/water)?

Whiskey11 said:

Sorry to double post but I figured I would update everyone about how stupid and stubborn I am! Yesterday I backed off the CPU core voltage down to 1.475V and let it run all day at 245x15 FSB (3.675GHz). Max temp recorded 55ºC after 9 hours of run. Today I'm feeling particularly narcissistic and decided to jump the FSB back up to 250 (3.750GHz) and let her rip without adjusting voltage. Prime95 is running right now so we will see how long it will go before it either crashes or posts an error! 10 minutes gone so far, still on the 4000 Lucas-Lehmer iterations but the 800,000's are up to really stress this bugger!

Wish me luck! Maybe the problem I've been having is having too much voltage! I'm curious trents, what's the highest you've seen a C2 945 125W go with "conventional" cooling (air/water)?

Click to expand...

There's no hard ceiling on how high any part will go. 3.7-3.8 is usually where these crap out. My 955 c2 went up to 3.85 at stock voltage, but wouldn't even get past post if I increased voltage.. I never could figure out if I was blessed or cursed with that chip haha. If you can run at 3.75, you're doing pretty well

Anonaru said:

There's no hard ceiling on how high any part will go. 3.7-3.8 is usually where these crap out. My 955 c2 went up to 3.85 at stock voltage, but wouldn't even get past post if I increased voltage.. I never could figure out if I was blessed or cursed with that chip haha. If you can run at 3.75, you're doing pretty well

Click to expand...

Good to know! Prime95 is still chugging away almost an hour later. Max temp in HWM was 56ºC during those 800,000k tests but it only peaked there. It hovered around 53-54ºC in those tests after peaking! I may try and go up more... we'll see! Of course my HTlink and CPU-NB frequencies are at 2000 so that may be part of the reason why I'm not having issues. It seems like anytime I go up on those above 2000 I get rounding errors galore in Prime95, even with tweaking voltages.