diff --git a/checkin_notes b/checkin_notes
index c076af1026..93079a7f2a 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -9157,3 +9157,16 @@ David  12 Nov 2009
         sched_array.cpp
         sched_score.cpp
         sched_send.cpp
+
+David  12 Nov 2009
+    - client: add new config options:
+        <ignore_cuda_dev>n</ignore_cuda_dev>
+        <ignore_ati_dev>n</ignore_ati_dev>
+        to ignore (not use) specific NVIDIA or ATI GPUs.
+        You can ignore more than one.
+
+    client/
+        client_state.cpp
+        log_flags.cpp,h
+    lib/
+        coproc.cpp,h
diff --git a/client/client_state.cpp b/client/client_state.cpp
index 52a70e10af..58a780bc11 100644
--- a/client/client_state.cpp
+++ b/client/client_state.cpp
@@ -261,7 +261,10 @@ int CLIENT_STATE::init() {
     if (!config.no_gpus) {
         vector<string> descs;
         vector<string> warnings;
-        coprocs.get(config.use_all_gpus, descs, warnings);
+        coprocs.get(
+            config.use_all_gpus, descs, warnings,
+            config.ignore_cuda_dev, config.ignore_ati_dev
+        );
         for (i=0; i<descs.size(); i++) {
             msg_printf(NULL, MSG_INFO, descs[i].c_str());
         }
diff --git a/client/log_flags.cpp b/client/log_flags.cpp
index dd8f35c2ce..e3edfa81e5 100644
--- a/client/log_flags.cpp
+++ b/client/log_flags.cpp
@@ -163,6 +163,12 @@ void LOG_FLAGS::show() {
     }
 }
 
+static void show_gpu_ignore(vector<int>& devs, const char* name) {
+    for (unsigned int i=0; i<devs.size(); i++) {
+        msg_printf(NULL, MSG_INFO, "Config: ignoring %s GPU %d", name, devs[i]);
+    }
+}
+
 // TODO: show other config options
 //
 void CONFIG::show() {
@@ -184,6 +190,8 @@ void CONFIG::show() {
     if (config.zero_debts) {
         msg_printf(NULL, MSG_INFO, "Config: zero long-term debts on startup");
     }
+    show_gpu_ignore(ignore_cuda_dev, "NVIDIA");
+    show_gpu_ignore(ignore_ati_dev, "ATI");
 }
 
 CONFIG::CONFIG() {
@@ -201,6 +209,8 @@ void CONFIG::clear() {
     exclusive_apps.clear();
     force_auth = "default";
     http_1_0 = false;
+    ignore_cuda_dev.clear();
+    ignore_ati_dev.clear();
     max_file_xfers = MAX_FILE_XFERS;
     max_file_xfers_per_project = MAX_FILE_XFERS_PER_PROJECT;
     max_stderr_file_size = 0;
@@ -227,6 +237,7 @@ int CONFIG::parse_options(XML_PARSER& xp) {
     char tag[1024], path[256];
     bool is_tag, btemp;
     string s;
+    int n;
 
     clear();
     while (!xp.get(tag, sizeof(tag), is_tag)) {
@@ -275,6 +286,14 @@ int CONFIG::parse_options(XML_PARSER& xp) {
             continue;
         }
         if (xp.parse_bool(tag, "http_1_0", http_1_0)) continue;
+        if (xp.parse_int(tag, "ignore_cuda_dev", n)) {
+            ignore_cuda_dev.push_back(n);
+            continue;
+        }
+        if (xp.parse_int(tag, "ignore_ati_dev", n)) {
+            ignore_ati_dev.push_back(n);
+            continue;
+        }
         if (xp.parse_int(tag, "max_file_xfers", max_file_xfers)) continue;
         if (xp.parse_int(tag, "max_file_xfers_per_project", max_file_xfers_per_project)) continue;
         if (xp.parse_int(tag, "max_stderr_file_size", max_stderr_file_size)) continue;
diff --git a/client/log_flags.h b/client/log_flags.h
index af75a92fc5..7139570121 100644
--- a/client/log_flags.h
+++ b/client/log_flags.h
@@ -114,6 +114,8 @@ struct CONFIG {
     std::vector<std::string> exclusive_apps;
     std::string force_auth;
     bool http_1_0;
+    std::vector<int> ignore_cuda_dev;
+    std::vector<int> ignore_ati_dev;
     int max_file_xfers;
     int max_file_xfers_per_project;
     int max_stderr_file_size;
diff --git a/lib/coproc.cpp b/lib/coproc.cpp
index 3c0e455268..25a596b184 100644
--- a/lib/coproc.cpp
+++ b/lib/coproc.cpp
@@ -137,40 +137,48 @@ void COPROCS::summary_string(char* buf, int len) {
     strcpy(buf, bigbuf);
 }
 
-
-#ifdef _WIN32
-
-void COPROCS::get(bool use_all, vector<string>&descs, vector<string>&warnings) {
-    COPROC_CUDA::get(*this, use_all, descs, warnings);
-    COPROC_ATI::get(*this, descs, warnings);
+static bool in_vector(int n, vector<int>& v) {
+    for (unsigned int i=0; i<v.size(); i++) {
+        if (v[i] == n) return true;
+    }
+    return false;
 }
 
-#else
-
+#ifndef _WIN32
 jmp_buf resume;
 
 void segv_handler(int) {
     longjmp(resume, 1);
 }
+#endif
 
-void COPROCS::get(bool use_all, vector<string>&descs, vector<string>&warnings) {
+void COPROCS::get(
+    bool use_all, vector<string>&descs, vector<string>&warnings,
+    vector<int>& ignore_cuda_dev,
+    vector<int>& ignore_ati_dev
+) {
+
+#ifdef _WIN32
+    COPROC_CUDA::get(*this, use_all, descs, warnings, ignore_cuda_dev);
+    COPROC_ATI::get(*this, descs, warnings, ignore_ati_dev);
+#else
     void (*old_sig)(int) = signal(SIGSEGV, segv_handler);
     if (setjmp(resume)) {
         warnings.push_back("Caught SIGSEGV in NVIDIA GPU detection");
     } else {
-        COPROC_CUDA::get(*this, use_all, descs, warnings);
+        COPROC_CUDA::get(*this, use_all, descs, warnings, ignore_cuda_dev);
     }
 #ifndef __APPLE__       // ATI does not yet support CAL on Macs
     if (setjmp(resume)) {
         warnings.push_back("Caught SIGSEGV in ATI GPU detection");
     } else {
-        COPROC_ATI::get(*this, descs, warnings);
+        COPROC_ATI::get(*this, descs, warnings, ignore_ati_dev);
     }
 #endif
     signal(SIGSEGV, old_sig);
+#endif
 }
 
-#endif
 
 // used only to parse scheduler request messages
 //
@@ -285,7 +293,8 @@ void COPROC_CUDA::get(
     COPROCS& coprocs,
     bool use_all,    // if false, use only those equivalent to most capable
     vector<string>& descs,
-    vector<string>& warnings
+    vector<string>& warnings,
+    vector<int>& ignore_devs
 ) {
     int count, retval;
     char buf[256];
@@ -474,12 +483,15 @@ void COPROC_CUDA::get(
         return;
     }
 
-    // identify the most capable instance
+    // identify the most capable non-ignored instance
     //
     COPROC_CUDA best;
+    bool first = true;
     for (i=0; i<gpus.size(); i++) {
-        if (i==0) {
+        if (in_vector(gpus[i].device_num, ignore_devs)) continue;
+        if (first) {
             best = gpus[i];
+            first = false;
         } else if (cuda_compare(gpus[i], best, false) > 0) {
             best = gpus[i];
         }
@@ -492,7 +504,9 @@ void COPROC_CUDA::get(
     for (i=0; i<gpus.size(); i++) {
         char buf2[256];
         gpus[i].description(buf);
-        if (use_all || !cuda_compare(gpus[i], best, true)) {
+        if (in_vector(gpus[i].device_num, ignore_devs)) {
+            sprintf(buf2, "NVIDIA GPU %d (ignored by config): %s", gpus[i].device_num, buf);
+        } else if (use_all || !cuda_compare(gpus[i], best, true)) {
             best.device_nums[best.count] = gpus[i].device_num;
             best.count++;
             sprintf(buf2, "NVIDIA GPU %d: %s", gpus[i].device_num, buf);
@@ -502,9 +516,11 @@ void COPROC_CUDA::get(
         descs.push_back(string(buf2));
     }
 
-    COPROC_CUDA* ccp = new COPROC_CUDA;
-    *ccp = best;
-    coprocs.coprocs.push_back(ccp);
+    if (best.count) {
+        COPROC_CUDA* ccp = new COPROC_CUDA;
+        *ccp = best;
+        coprocs.coprocs.push_back(ccp);
+    }
 }
 
 bool COPROC_CUDA::is_usable() {
@@ -758,7 +774,7 @@ int (*__calDeviceGetInfo)(CALdeviceinfo*, CALuint);
 #endif
 
 void COPROC_ATI::get(COPROCS& coprocs,
-    vector<string>& descs, vector<string>& warnings
+    vector<string>& descs, vector<string>& warnings, vector<int>& ignore_devs
 ) {
     CALuint numDevices, cal_major, cal_minor, cal_imp;
     CALdevice device;
@@ -947,25 +963,33 @@ void COPROC_ATI::get(COPROCS& coprocs,
     // same as for NVIDIA
 
     COPROC_ATI best;
+    bool first = true;
     for (unsigned int i=0; i<gpus.size(); i++) {
         char buf[256], buf2[256];
-        if (i == 0) {
-            best = gpus[i];
-        } else if (gpus[i].peak_flops() > best.peak_flops()) {
-            best = gpus[i];
-        }
         gpus[i].description(buf);
-        sprintf(buf2, "ATI GPU %d: %s", gpus[i].device_num, buf);
+        if (in_vector(gpus[i].device_num, ignore_devs)) {
+            sprintf(buf2, "ATI GPU %d (ignored by config): %s", gpus[i].device_num, buf);
+        } else {
+            if (first) {
+                best = gpus[i];
+                first = false;
+            } else if (gpus[i].peak_flops() > best.peak_flops()) {
+                best = gpus[i];
+            }
+            sprintf(buf2, "ATI GPU %d: %s", gpus[i].device_num, buf);
+        }
         descs.push_back(buf2);
     }
+    best.count = 0;
     for (unsigned int i=0; i<gpus.size(); i++) {
-        best.device_nums[i] = i;
+        if (in_vector(gpus[i].device_num, ignore_devs)) continue;
+        best.device_nums[best.count] = i;
+        best.count++;
     }
 
     COPROC_ATI* ccp = new COPROC_ATI;
     *ccp = best;
     strcpy(ccp->type, "ATI");
-    ccp->count = numDevices;
     coprocs.coprocs.push_back(ccp);
 }
 
diff --git a/lib/coproc.h b/lib/coproc.h
index fadceb938c..8133480111 100644
--- a/lib/coproc.h
+++ b/lib/coproc.h
@@ -176,7 +176,9 @@ struct COPROCS {
 #endif
     void get(
         bool use_all, std::vector<std::string> &descs,
-        std::vector<std::string> &warnings
+        std::vector<std::string> &warnings,
+        std::vector<int>& ignore_cuda_dev,
+        std::vector<int>& ignore_ati_dev
     );
     int parse(FILE*);
     void summary_string(char*, int);
@@ -249,7 +251,8 @@ struct COPROC_CUDA : public COPROC {
     virtual ~COPROC_CUDA(){}
     static void get(
         COPROCS&, bool use_all,
-        std::vector<std::string>&, std::vector<std::string>&
+        std::vector<std::string>&, std::vector<std::string>&,
+        std::vector<int>& ignore_devs
     );
 	void description(char*);
     void clear();
@@ -311,7 +314,8 @@ struct COPROC_ATI : public COPROC {
     COPROC_ATI(): COPROC("ATI"){}
     virtual ~COPROC_ATI(){}
     static void get(COPROCS&,
-        std::vector<std::string>&, std::vector<std::string>&
+        std::vector<std::string>&, std::vector<std::string>&,
+        std::vector<int>& ignore_devs
     );
     void description(char*);
     void clear();